The only game outside the M&M series that I rated as highly was Eye of the Beholder 2 – the Legend of Darkmoon. Although a superb game, its weakness was that the pleasure of replaying it fell quite sharply, because you always found exactly the same weapons, armour, and other items in exactly the same places in every game.
In contrast, I'll never forget the time when the random generator in MM3 presented me with an acidic obsidian longsword. Weapons like that were as scarce as hens' teeth. If you mephistoed one of the high-tariff treasures such as the treasure piles in the depths of Dragon Cavern, you might get one in a full afternoon's work. But I wouldn't guarantee it.