Uncirculated specimens have greater detail due to the lack of wear and therefore command the most money at auctions, but is there a particular coin (or type) that you feel looks nicer with wear as opposed to uncirculated? In my opinion, I think old nickels can sometimes be more attractive than uncirculated examples. I don't know if it has to do with the rounder edging, but they sometimes catch my eye. I also like the distinct color they get with age and wear.
I don't know about nicer, but I do like a good "circulated cameo" look. It seems to kick in around EF 45 and last down to VF 35. Much below that, and it the coin just looks worn (not that there's anything wrong with that).
Waiting for obligatory reference to SBAs ... I will admit something somewhat contrarian in that I quite prefer the look of nicely circulated cameo Morgan Dollars. It makes them cheaper too! edit - lol @Paul M. beat me to it as I was uploading my image!
The Eunice Shriver commemorative would look better worn. In fact, it would look best after being run over by a train.
