For me:

1. Shadow Over Mystara

2. Pool Of Radiance

3. Neverwinter Nights

SOM is my favorite arcade game of all time as well as beat 'em up, the cherry on top is that it’s a D&D game. Does it follow the rules and mechanics of the game? Hell no, but it’s fun in that it’s the soul of the game mixed with fighting game mechanics.

Pool Of Radiance is the only Gold Box game I’ve beat so far. It’s primitive but it really does the rules and campaign of AD&D justice. Best to play it with the Gold Box Companion that maps the game for you.

NWN is great since it’s 3D D&D while like POR it sticks to the rules of 3.5 D&D. Plus it allows you to make your own campaign if you wish or play fan made ones (some of which are really good and outshine Bioware’s own).