Favorites:
    Zul'Furrok: the epic battle on the stairs has got to be one of the best ones in the game...very cool, and love helping lower lvls w/ that :P
    Sunken Temple: another good battle w/ the dragons where you gotta flick the candles on, and its repeatable :P
also, nice trink from killing Eraknus

Hated:
    Uldaman!!!!! grr! so confusing! although i like the back door, which helps a lot if you keep dying half way throught the instance :P
    Gnomeragon...the boss isnt really a boss i guess, although its worth going in just to get some of the jewels...