Hmmm, you may scan back in time on this forum under both the Louisville or Lexington sections and you will the exact same question posted numerous times from other members. I remember reading them myself since we are also between both places. Obviously it's subjective. Terrain wise around Lexington you have gorgeous rolling mild hills spotted with intermittent trees and lined with the most incredible horse properties you will ever see. I really liked the area to the south by Nicholasville. Schools are also good in that area if you have kids.
Now the terrain around Louisville, especially to the south and east, is practically a forest with houses dispersed around and in them. More tree covered streets. Lexington is more spread out, while Louisville is more dense once you get to the city part in Jefferson County. Were in love with Oldham County for it's beauty and top rated public school system. Check out my pictures I posted on this site [under: "I'm back from....", 2 parts] with lots of pictures of the incredible beauty. I also have created a set shown on
Welcome to Flickr - Photo Sharing (http://www.flickr.com - broken link), just type in Oldham County, Kentucky on there search engine, you will see lots of mine and others. I'm called the "Wandering Photo Nut".
The only thing missing in my eyes for Oldham county is the lack of any larger towns, all the towns are more Bedroom Communities than towns. But all were nicely created with nature in mind, a lot less of the track home style suburbs being created around most cities [especially true with most of N. KY].
Both cities are located near rivers which is nice, Louisville being more a real micropolitan type city, and Lexington being more like a nice smaller city that has just expanded "out". I haven't had a chance to explore the eastern side of Lexington yet, so that area is still a unknown for me.