I'm going to say Wizardry 8, only because out of everyone I've ever met and discussed RPGs with (which is a fair number, I socialise in circles that argue about how magic should function), I am the only person besides one who has heard of it, and therefore, played it. I know the Wizardry series got quite a following but if that died with 8 I don't know, since no one seems have heard of it.
For those who haven't, it's fantastic and you should go download / purchase a copy now. SirTech are liquidised (have been for a few years) so pirating it wouldn't hurt anyone even though copyright is still technically enforced, it's almost impossible to buy retail now.
The graphics are very simple 3D through the eyes of your collective party, much akin to Morrowind with simpler textures (though there are some nice reflections in places). Character creation is inventive, complex (though not difficult) and liberating. Theres a host of races and classes to choose from, lots of freedom to choose characteristics most of which you tend to become quite attachted to once the epic quest is over, and a myriad of skills and spells. The world is open though much is travelling through wide corridors of countryside path, there are hundreds of unique NPCs to interact with many of which provide an array of sidequests that are never repetative or linear fetch and or kill x enemy ordeals. It's just a really solid, really entertaining RPG that should have sold a lot better than it did so we could have Wizardry 9. It is also one of few games that pulls of making choices well, it's not black and white, evil and good, paladin and necromancer, picking sides or uniting warring factions, making decisions that deeply impact personal relationships. It's all very well thought out. The main quest is quite high fantasy and doesn't get dull for a moment, there is some great voice acting, annnnd that's all I have to say.
Get Wizardry 8, you won't regret it. Especially since you can get it free >.>