I like Georgia's new plates, very clean look to them. I was SO glad when they got rid of the silver fade from the 2005-2007 era, those were UGLY :
http://www.15q.net/us1/ga04.jpg
However, I liked the 1998-2005 ones better though, mainly because they had "Georgia...On my Mind" on them:
Colorado's plates are classic and iconic.
California's are nice, but dull. The only other state I know that uses the 'lipstick' font is Louisiana.
But this is my favorite Cali plate (from 83-87):
The art deco lettering and the sun and the lines that make up the horizon are what do it for me.
Arizona is another favorite. I usually hate 'busy' plates, but the colors and the cactus scream "Arizona" to me.
DC's "Taxation Without Representation" plates are plain jane, but I love them just for the snarky slogan.
Michigan's "Great Lakes Splendor" specialty plates are nice.
I love Tennessee's new plates. Absolutely gorgeous. I do kinda miss the "Sunny side up" plates though:
http://www.15q.net/us5/tn01a.jpg
...But I HATED the smiling sun on Kentucky's plates. Cheesy cheesy cheesy!
Maryland is another favorite of mine. They have the best state crest and flag to me, so having it on their plates is icing on the cake for me. And it's simple and clean.
Florida's plate looks like it was made on MS Paint. Boooooo! But they have millions of specialty plates, I swear!
Mississippi has usually had nice plates over the years. The new "Biloxi lighthouse" one is great, and it's a great tribute to the Gulf Coast. MS was one of the first states in the 70's to use a graphic (the iconic magnolia) and a slogan.
I actually like New York's plate. I'm pretty sure they couldn't have NYC dominate all over the plate without upsetting the Upstate, so they compromised pretty well.
New Jersey's plate still looks good, and it doesn't look dated for it to be from the 90's.
North Carolina's plates look dated to me.
Rhode Island's are simple, but get the point across.
South Carolina's plates that had "Smiling Faces Beautiful Places" are nice too.
I hate Delaware and Indiana's flat plates. I miss the "Crossroads of America" plates they used to have in the late 90's/early 2000's.
As For Canadian Provinces, I HATE Alberta's plates. They're stuck in the 70's: