I've flown on the ERJ and ER3 with Continental and American and the CRJ and CR7 with Delta. I would rank order them this way...
CRJ flight was from Cincy to Knoxville. It was loud, cramped, and generally uncomfortable. The CR7 is a BIG improvement.
ERJs, especially on the A side or C side if the seat next to you is vacant, are quite pleasant. The overhead bins held my bags, I didn't feel the need to duck down too much (I am 6'1"), and the seats are quite comfy. The longest route I've flown was IAH
-Montrose Colorado. That's a little over two hours and I didn't mind one bit. Don't think I'd want to try it all the way to Boise though...