My Fav was prolly the first one I really sank any time into and stopped playing CS/CS:S for.
Dark Age of Camelot - Pre Trail of Atlantis.
I loved that games and I still think Darkness falls is one of the best idea's for a dungeon, problem was after TOA I just spent all my time farming high end scroll with my Necro and a mates repec'ed cleric, which got old.
Never realy enjoyed anything the same since. Currently playing WAR but I'm finding it a little hard going, I enjoy T1 and T2 but the grind from T3-T4 has so far beaten me, hence I have a level 17-20 a lot of most class's.
I have Darkfall to try but I aren't sure about it yet, there are too many things that look and feel wrong. It has potential but I wouldn't be suprised if it goes under before that potential is realised.
I'm almost tempted to put WoW back on, god forbid! I wish I had just sold the accounts to temptation was removed
Cheers.