And now the Holy Handgrenade: Try Ultima IX. Bugs and glitches everywhere, as an Ultima game it is simply horribly wrong but it has it's good sides as well. I guess it's one of them games you either hate, period, or love for the awfulness unless you are duped by the 3D, glittery graphics and just love it. Am I serious about suggesting you to try it? Absolutely. Check it out and see for yourself what that game is about.
Other than that: U7 is one I never got around to finish but I remember it to be an absolutely fantastic game, with the huge world where I could do, if not anything, then at least way more than I could in any onther game I had tried back then. U8 I did finish and it's not bad, far from it, but I still prefer U7, with the travelling Party unlike U8, where Avatar was a loner running around. Last: The Ultimate Ultima game is still U Underworld 1
Nearly everything was done right in that game, the atmosphere, the gameplay, the interface, the magic, it was near perfect.