Actually, I think I'd probably have Planescape: Torment already, were it not out of print.
Amazon has pretty inexpensive boxsets, now, of both the Icewind Dale series & the Baldur's Gate series (4 in 1 for the latter)... but I'm not really smitten with BG, yet, at least as far as I've played of Tales of the Sword Coast . . . the game actually seems too demanding in regard to how much attention you have to pay to your companions in order to make sure they don't die (one annoying wizard has already died on me because he decided to attack a creature in melee; I finally decided to leave his corpse behind and head on to the Friendly Arms Inn without him . . . good riddance), and... based on the level the characters are at in the game-embedded expansion-ready party: it looks like you gain too few levels too slowly.
...But I'm sure I'll go back into it soon, and maybe my feelings will change.
Note to UK players.
The lazy publishers just dumped these sets onto disc, without checking the versions.
They`re the US versions of the game, and refuse to run on a UK machine, but luckily, they can be patched to the UK version, links still available on the BG forum.