Sorry awhshopgirl, if he has Wiz8 now and loves it, he'll be disappointed with everything else! Sorry, I just don't like the combat style of most of the above mentioned games. See if he likes Pool of Radiance and if he does, I would suggest Temple of Elemantal Evil. The combat style is the same, which is great, but it is a fairly short game.
Planescape gets a lot of high marks on the forum and I think the combat is turn-based, which he'll probably prefer. But you just can't beat a game where, if you know you can kick butt, just go to the kitchan and get a snack and when you get back the baddies are dead... Love Wizardry 8!