True, I had the BG series before I had my GoG.com account.

So Ithereof my favourite game that I only have a GoG copy of would be Planescape: Torment. Though I believe I'll enjoy Icewind Dale as much, once I eventually get to playing it.

I have other GoG's, but I simply love the Infinity Engine game series; I even love the graphics thereof more than I love the beautiful graphics in Neverwinter Nights, despite the latter having more universally appreciated visuals.

Either Tex Murphy - Pandora Directive (honestly, if you haven't played this game yet, shame on you. Shame on you twice, in fact).

Or Gothic II.

Commandos 2 all the way baby ! F**k yeah ! xD

I'm (EDIT) *not* so sure that it is! I thought the Gold thing was about having the Underworld expansion together with the game in one purchase, also with a few bugs fixed (possibly). Something like that anyway. I know that you can no longer use the cheats on Sacred Gold that you could once use on the regular, original Sacred. Although saying that, someone has put together a pretty cool trainer for the game, which is linked in the forums here.

It's probably not a massive deal.

Fallout 2, Homm3,all Unreals..

For me, Evil Genius.

neverwinter nights

Baldur's Gate 2

Just because of the Wild Mage. You want to cast Magic Missile? fuck you! We're changing gender!

Planescape Torment, and Psychonauts.

Baldur's Gate 2 is one of my favorite games of all time, but I've been playing that for a decade now. The two above were my first two purchases here, and so far, my favorites as well.

Baldur's Gate 2 is probably the game I've put most time and love into, but I have no hesitation saying Planescape: Torment is my favourite game GOG or otherwise. I don't think I have to explain why, I'm sure someone else has mentioned it once or twice.