First and foremost, Wizardry 8. I don't think it's as good as MM, but at least it has a Windows interface.There are better ones further back if you can handle a DOS interface.
See if you can find a copy of MM6 limited edition on eBay. That has MM1-5 and Swords of Xeen on it as well. MM3-5 are good games. Also, Eye of the Beholder I (EOB1) and The Legend of Darkmoon (EOB2) were both cracking games. EOB3 (The siege of Myth Drannor, IIRC) is not as good, but still worth playing.
Added to those are Ultima Underworld 1 & 2, and you could also have a look at the earlier Wizardry games, Bane of the Cosmic Forge and Crusaders of the Dark Savant.