Knowing DnD isn't really a big deal with Planescape Torment since not only does it take place in a more obscure setting largely unhindered by DnD tropes but also because combat and rulesets are really just such a minor part of the game. A minor and pretty mediocre part, combat is not Planescape's strength at all. In truth it's easier to think of Planescape: Torment as an interactive book that also just happens to be in an isometric rpg game engine rather than as a DnD game itself. I mean it *is*, but that's not why any sane person plays the game, they play it for the story which itself can be fully appreciated on its own.
Planescape aside it's funny seeing Divine Divinity up there. Good game, great even, but it's not really like any other game on your list. It's more Diablo than Baldur's Gate or Fallout. Combat oriented non-tactical gameplay, very well done but also an entirely different beast than the other games. So really if you're looking for something more actiony that'd be a great pick.
Personally however I choose
(predictable although it might be) Baldur's Gate. For someone new to DnD its almost guaranteed to be teeth gnashingly hard at the start and bound to be the source of some frustration, but that said it's also probably the most well balanced game of the list and easily one of the most satisfying. The story is excellent, the characters memorable, the combat entertaining and nicely tactical, and it even looks nice once you'd updated the resolution. Just a really well done all-round experience and in my opinion Bioware's best work to date. Other games might do one or two things better but the BG games are just the whole experience, I like that!
Icewind Dale meanwhile is a more combat heavy plot-lite version of BG above. Same engine, same combat, less story. So if you like the combat as many people did and still do the Icewind Dale series are fantastic. But if you're not sure yet... I'd save them for later.
Hope that helps!
ThoughtlessConcept said:
Unless you want to do the engine update on BG1 I'd just read some backstory and then play BG2, the engine update take fooooorrrreeevvveerrr.
Takes about an hour on my computer and certainly worth the time spent, especially since it opens up the possibility of amazing mods like
BG1 NPC Project and
Unfinished Business both of which I extremely highly recommend even for a first playthrough. Besides Baldur's Gate 1 is a fantastic experience, why push it aside just because the mods can take awhile to set up?