The Nexus is my 2nd Android device and came to it from the Incredible. I was a big fan of roms, switching constantly between CM & Sense based ones. When I was running a CM rom, I was trying to make it look as nice as Sense.
Now that I am running ICS, I have no desire for it to look like anything else and I actually don't miss Sense (I know, I know, many people hate it but it really was the best looking of them all). That said, for me to leave behind my Nexus, I would need a pretty remarkable change to one of the OEM 'skins', and a phone the same size. I compared my DInc to the Nexus today and couldn't believe how small my phone was before. It will be tough to leave the size of this phone and the clarity of picture.
What's my next phone? The UI has to be as, well, pretty as 4.0, 4.5" or bigger, considerably faster, better camera but keeping the functionality of the Nexus camera, and the ability to correctly sync and merge my contacts from G+, Facebook, Twitter, email and whatever other social item is out there at the time.