My personal impressions with classes:

1. Crusaders = great and easy, especially with stampede-based build
2. Monks = great, slightly harder to manage than Crusaders, but still very viable
3. WD = easy to play (especially zoomancer builds), but slooow to kill anything + problems with pets AI (path-finding, doing nothing, etc). Too much fetishes = mess
4. Barbarian = hard to keep in sync, waiting for 2.2 patch to check perma-ancients build with whirlwind to avoid sync problems
5. DH = squishy, hard to keep in sync