Wizardry 8 is excellent if you like old-style RPGs, some complain that it is too combat-focused, but it has nearly infinite replay capability, good NPCs, and its very pretty (3D environment, 1st person, real time).
http://www.wizardry8.com/
(Yeah SIR-TECH! I even got a Apple IIe emulator so i could play the original Wizardry, although that was before Wiz8 came out. Sadly, they are no more.)
If you don't mind a 2d environment, the Exile trilogy is really really good, excellent storyline, flexible character development, and with the Blades of Exile Version, players can make their own adventures, some of which are really huge and complex.
http://www.spidweb.com/
Exile 1 and 2 have pretty bad graphics, 3 and Blades are better.
Avernum is the Exile trilogy expanded and remade, with the bonus of a quasi-3D projected environment.