This thread really brought back some fond memories, so thanks to the original poster. I started with the Gold Box games and have played basically everything to come out since then. Here's my list:
1--BG2: Perfectly designed and perfectly executed. It is the pinnacle of the CRPG genre and the game all others strive to immitate. Bioware set the bar very high... perhaps too high for their own good, as everything they do will be compared against this game.
2--Deus Ex: Although some might scoff at it being labeled an RPG, this game (like no other before or since) tricked me into "believing" I was one bad-a$$ mofo of a cybernetic demi-god. Also, Warren Spector's writing and story rival anything ever done in gaming on any platform.
3--Planescape: Although I may have enjoyed this game as much (or more) than any other game in my top ten list, the fact that it is basically an RPG/Adventure forces me to deduct a few points when compared to choices 1 and 2.
4--Daggerfall: This is the first game I played that felt like digital crack to the point that I simply couldn't step away from the computer screen except to eat, sleep, and relieve myself. It was immersion at its quintessential finest.
5--Realms of Arkania: Star Trail: The Dark Eye games are simply brilliant, and this was the best of the bunch. Try to imagine a game with the party-based tactical combat of a Wizardry and the deep story of a Baldur's Gate. Tremendously fun and addictive game with one of the legendary Fat Man's best midi soundtracks.
5--Fallout 2: Although Fallout 1 is a more complete and compact adventure, Fallout 2 has all that icky R-rated edginess that just really lights my candle.
6--Arcanum: This game is the essence of Troika: with deep role-playing, excellent story-telling, and a fully realized world that can be explored in whatever manner you see fit. Playing this game as a sword and gun wielding technologist was pure RPG bliss.
7--Icewind Dale 2: For some, this might be seen as a strange choice, but in many ways this epitomizes how to use a real-time pausable combat system. For me, a great CRPG combat system 1) begs for multiple replays, and 2) is extremely challenging without being frustrating. This game achieved this happy medium better than any game I've ever played.
8--Fallout 1: There's no need to explain why this is in my top ten. If it isn't in yours, you simply haven't played it yet, so shame on you.
9--Shadows Over Riva: Although missing the overland travel of Star Trail, this Dark Eye game still had a world of Das Schwarze Auge charm. Cheese toast anyone?
10--Pools of Darkness: Was there any gaming moment more fun than traipsing around within the god Moander's beating heart? Add to that some of the best gfx and combat ever to grace a Gold Box SSI 3.5 diskette and you've got a package that kept me busy for many, many months.