This is a very tough poll for me. I grew up in a conservative part of rural Pennsylvania, and as an openly-gay male I couldn't wait to leave after college. I initially moved to Northern Virginia, hated it immensely for a myriad of reasons, and was again searching for a greener pasture after living there for about 1.5 years. Through a metric ton of research my final two contenders ended up being Minneapolis/St. Paul or Pittsburgh.
I chose Pittsburgh primarily for three reasons:
1.) Less expensive rent, making it easier to "start over".
2.) Less geographically isolated, making "escapes" for weekend getaways easier.
3.) Milder winters, letting me enjoy running outdoors for a longer portion of the year.
With that being said if I was of a higher socioeconomic status; didn't feel the nomadic "itch" to take day-trips and weekend trips several times per year; and was content with running on a treadmill at a gym (don't like running in place), I'd be perfectly content living in the Summit Hill neighborhood of St. Paul or Loring Park or Dinkytown in Minneapolis.
Here's how I'd make selections based upon the given criteria from the OP:
NIGHTLIFE: Strong Edge to Minneapolis/St. Paul.
Pittsburgh is great if you're looking to get hammered from cheap beer at dive bars, especially the famed strip along East Carson Street in the South Side Flats; however, when it comes to "hitting the town" or "hittin' up the clubs" our city is severely lacking overall. When I want to go out dancing I have the same few "go-to" locales and very little else. I don't drink beer, and it seems like most bars in Pittsburgh charge an excessive premium for those of us who want a cocktail instead (and often those cocktails aren't very potent).
CULTURE: Draw/Tie.
For a city of just ~300,000 Pittsburgh punches WELL above its weight in terms of culture due to the philanthropy of our former industrialists like Frick, Mellon, and Carnegie. We have the Andy Warhol Museum; the Carnegie Museum of Natural History; the Carnegie Museum of Art; the Carnegie Science Center; the Pittsburgh Childrens' Museum; Phipps Conservatory; the National Aviary; Pittsburgh Zoo; PPG Aquarium; and an array of great theaters and performance venues Downtown in our Cultural District to host our symphony, ballet, and off-Broadway shows. We also have emerging "artsy" neighborhoods with lots of artisan gift shops and galleries, such as Lawrenceville, the Strip District, and Garfield, as well as artists' colonies like the Mattress Factory and the Manchester Crafstmans' Guild on the North Side.
Minneapolis/St. Paul ALSO has a plethora of culture and is often right up there with Seattle and Boston for claiming the title of the nation's most literate and/or most-educated city. Just off the top of my head you have Cowles Conservatory and the Minneapolis Sculpture Garden; Walker Art Center; Minnesota Childrens' Museum; the Science Museum of Minnesota; the Minnesota History Center; and a variety of theaters in the Downtowns of both St. Paul and Minneapolis. I'm sure I'm missing MANY more that the Minnesota boosters in this thread will elaborate more upon.
SHOPPING: Slight Edge to Minneapolis/St. Paul.
There's just no competing with the Mall of America, to be quite frank. Pittsburgh's "best" mall is arguably the Ross Park Mall, which has a variety of upscale stores like Swarovsky, Burberry, Godiva, Apple, Nordstrom, etc.; however, our other malls are either typical "run-of-the-mill" malls, or, in at least two cases (Century III Mall and the Galleria at Pittsburgh Mills) seemingly in decline. In terms of neighborhood shopping BOTH metropolitan areas have great walkable shopping districts---Uptown Minneapolis; Summit Hill in St. Paul; Downtown Edina; etc. AND Pittsburgh's Shadyside; South Side Flats; Squirrel Hill; Strip District; Lawrenceville; etc. Both Downtown regions are lacking in retail (although Pittsburgh has been improving on this front---not sure about Downtown Minneapolis or Downtown St. Paul, although I know Downtown Minneapolis has a newer Whole Foods).
DINING: Draw/Tie.
Anyone who makes the claim that dining options are far superior in one metropolitan area vs. the other is being disingenuous. Both cities are pretty evenly matched here and feature restaurants offering cuisines from all over the world.
SCENERY: Draw/Tie.
I'm always going to be a "homer" when it comes to favoring Pittsburgh's skyline. There's simply nowhere in Minneapolis with a high enough elevation to offer such a dramatic vista of Downtown as Pittsburgh's Mt. Washington. In terms of natural splendor, though, I love the "chain of lakes" in Southwest Minneapolis. I often fantasize about taking a vacation to Minneapolis and running around Lake Calhoun one morning; Lake Harriet the next; and then Lake Nokomis on a third day. Summit Hill in St. Paul is just beautiful, too. Pittsburgh's very steep terrain provides more stunning vistas, overall, but I feel like the lakes in Minneapolis are cleaner for outdoor recreation whereas I'm always turned-off to to the notion of kayaking around the rivers in Downtown Pittsburgh because our sewage system pumps poop into the rivers if it rains too hard (gross!)
OUTDOOR ACTIVITIES: Draw/Tie.
Again the cities are pretty evenly-matched here. Minneapolis residents greatly enjoy and utilize their lakes to the same extent that Pittsburghers greatly enjoy and utilize their rivers. Just east of Pittsburgh are the Laurel Highlands, home to Ohiopyle State Park, which offers great whitewater rafting, mountain biking, and hiking in the literal backyard of Frank Lloyd Wright's "Fallingwater" home. I can't think of any ski resort in/near Minneapolis/St. Paul that's as popular or as highly-elevated as Seven Springs in the Laurel Highlands, which attracts skiers from the Washington/Baltimore area, too. Minneapolis residents DO seem to appreciate their harsh winters more whereas Pittsburghers moan and complain about them, as is typical for the whining of Pennsylvanians in general. Both areas have great golf courses and beautiful city parks. I can't give the solid edge to either region here.
CRIME RATE: Draw/Tie.
It seems like some years Minneapolis/St. Paul is safer than Pittsburgh and then other years it's vice-versa. Both cities have a strong middle-class still residing in the city cores, which is a good stabilizing factor in helping to keep their crime rates reasonable. I'd probably feel as safe in Summit Hill in St. Paul as I'd feel in Squirrel Hill in Pittsburgh and about as safe in Dinkytown in Minneapolis as Oakland in Pittsburgh. There are some rough parts of North Minneapolis. There are some rough parts of Pittsburgh's East End, especially Homewood. I doubt either city blows the other out of the water for personal safety. As in most areas crime tends to spike in summer when the miscreants aren't deterred by the cold weather.
ECONOMY: Moderate Edge to Minneapolis/St. Paul.
Pittsburgh has a very stable employment picture right now, but wages at top employers, especially UPMC and PNC, are paltry, to say the least. I don't consider the economy to be rosy/healthy if nearly everyone is employed, but a large chunk of those who are employed aren't being paid commensurate with their skills, talent, work ethic, and expertise, as is the case with many Pittsburgh companies being highly-profitable (billions of profits for UPMC and PNC annually) while paying many front-line employees <$10/hr. Whenever I review GlassDoor or Salary.Com it seems like just about EVERY position in Minneapolis/St. Paul pays considerably more than in Pittsburgh, yet the cost-of-living isn't THAT much higher in Minneapolis/St. Paul, especially over the past few years since Pittsburgh has become "trendy". Pittsburgh, like Minneapolis/St. Paul, is a very highly-educated and literate city, yet I know many fellow college graduates who are still making $30,000/year-$40,000/year a decade after entering their fields. That's just disgusting. I can't be proud of Pittsburgh's strong job creation when so many of these new jobs don't pay much more than a living wage. Since both cities have strong job markets the edge will go to Minneapolis/St. Paul because their major corporate employers (Target, Best Buy, 3M, etc.) are known for treating their employees much more fairly than UPMC/PNC.
PEOPLE: Moderate Edge to Minneapolis/St. Paul (Perception).
I moved to Pittsburgh partially because I found the pretense, competitiveness, and smugness of many in Northern Virginia to be overwhelming. I was told how Pittsburghers were amazingly friendly and down-to-earth. After living here for nearly five years I can say that Pittsburgh is friendly compared to DC, Boston, NYC, etc., but on a national scale it's no friendlier than most other medium-sized cities. I think perceptions are clouded here because so many newcomers to Pittsburgh are FROM the BosWash Corridor, where they think "rude" is the "norm". I'd rather live with the "Minnesota Nice" of people smiling to my face and being congenial before slandering me behind my back rather than the Pittsburgh bluntness where people are in-your-face and hostile. Just this morning we did laundry in Bloomfield, that much-lauded neighborhood in a prior reply to this thread, and my partner said "Good morning" to three separate people who were sitting on stoops staring at him (he has one arm) between the laundromat and Starbuck's, and not one of the three people said anything back. I work as a food delivery driver, and the majority of my clients treat me like I'm "beneath" them. I've really found that Pittsburgh has a ton of horrible jerks, but, alas, we're "super rad friendly" just because we're better than some of the country's rudest cities.
WEATHER: Draw/Tie. (All Based Upon Personal Preferences).
I don't like Minnesota winters. I don't like Pittsburgh winters. With that being said I'd rather it be -10 degrees and sunny with blue skies (Minneapolis) than +10 degrees with overcast skies for days on end (Pittsburgh). I find it depressing in the winter here that not only is it very cold, but you also DO genuinely go days at a time without having a sunny day (Craziaskowboi is a Pittsburgh "booster" who will call a day that is 25% sunny a "sunny day" whereas I'd still consider that to be a "cloudy day"). We're usually too far northwest from Nor'easters to get much snow (the one in early-2010 with the surprise last-minute wobble that dumped two feet being the exception), but we're still close enough to get the clouds. I don't want to spend anytime outdoors running, cross-country skiing, sledding, etc. in the winter here if it's overcast and dreary-looking. I just get depressed. If Pittsburgh could have more sunshine, I'd be thrilled. As it stands now I'm looking out my window at MORE clouds and just want to crawl back in bed instead of heading off to work.
QUALITY-OF-LIFE: Draw/Tie.
Sometimes Minneapolis/St. Paul is "America's Most Livable City". Sometimes Pittsburgh is. Sometimes Honolulu is. Overall the cities are VERY evenly-matched in many rankings, so it's unfair for the Minnesota boosters on here to be saying they crush Pittsburgh on everything, like juvenile idiots. Believe me, I did EXTENSIVE research into BOTH AREAS in 2010 because I need to get out of Stepford---I mean NoVA---and I came very close to living a happy life in St. Paul instead of Pittsburgh. Both cities are very underrated on a national scale. People just think of Minnesotans as "white people who are always freezing", and people don't know anything about Pennsylvanians and just sort of shrug because we're overshadowed by NY/NJ. Both perceptions are highly inaccurate.