1> Ultima On-line (abandoned) pro's - no 'set' classes, con's - got too 'old' technology-wise
2> Guild-Wars (semi-abandoned) pro's - everything, especially "salvaging" system, con's - ALL expansions required purchasing.
3> World Of Warcraft (abandoned) pro's - auction houses, con's - gets boring easy, no real CHARACTER storyline.

I no longer really MMO much, I play Evony (but that dont count as a real MMO IMHO).
I now design, and am SLOWLY working on a MMO that takes inspiration from all three of
these games, plus freshly created content.