Not a big fan of RPG's as not one yet has had a story line i was vuguely intrested in and wasnt a load of drivel ( and i use to play paper DnD :P ) But i recomend the ones i played
oblivion RPG its fun but pretty bog standard rpg decent graphics.
EVE RPG mmo - i found it incredably borring and didnt find anything in it worth playing but thousands if not more think its uber.
planetside FPS RPG MMO - best game i played ever mmo single player etc it isnt that good any more due to sony owning it but still an excellent game and a 300 player battle with good commanders cannot be replicated in any other game.
WoW & EQ & EQ2 MMORPG's - basic RPG bit borring WoW runs on weak systems as does eq1, EQ2 is pretty but same old same old.
Best fantasy based RPG MMO for me was dungeons and dragons online - excellent fun if you like to play and work as a team but very lacking in content and i found some of the content dull and if you really play it does become very repetative.
best RTS i played and i cant say why because its not even a full game its so basic sadly but still love it is Sid Mears Railroads.
But the game i play most these is real money texas hold'em poker

its a kinda RPG FPS RTS MMO :P