Favorite
East 757 -- they've been looking a bit worn recently, but I've been flying them since before US had the A321s and they've always been my first choice transcon (admittedly less-so with the FC reconfigurations)

Least Favorite
Dash-8 -- they may be sturdy little planes, but they're much too loud for a flight from ROA (my home airport) to PHL. I go out of my way to fly through CLT since the Dash-8 is the only thing they fly out of here to PHL.