For me:
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Shadow Over Mystara
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Pool Of Radiance
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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).
BG3 is an all around solid game with a decent amount of polish, and while the main story is pretty boring and predictable, as with most Bioware-style games the real story is in the companions, and they're a good enough selection that most players will be able to pick out a party without having to use anyone they really hate. I would still say that I had more fun talking about the game than actually playing it.
I played Lords of Waterdeep with the Skullport expansion exactly once at a friend's house and it was alright. It's a worker placement boardgame and tbh the branding didn't really do much for me because I don't know or care about anything in the Forgotten Realms, much less Waterdeep specifically.
BG1 is a boring game with a simple and uninteresting story, and really does a great job of instilling a hatred of the Vancian casting system in the player. Turns out a 1:1 implementation of AD&D's rules makes for a bad game, who knew. The only reason this takes #3 is because I actually finished it.
Also started but never finished BG2 and NWN2 (didn't get far in either), and played a little of the Neverwinter MMO and DDO but stopped quickly because neither were good. I actually own Planescape Torment but have never actually brought myself to play it. EDIT: saw someone mention BG Dark Alliance and I did also play that for several hours at a friend's house once. It should probably be in third but the fact that I forgot means it obviously didn't make much of an impact.
I will close by saying that WOTC should canonically blow up the Sword Coast so that they can set games elsewhere for once.
I'd be down with a new Mystara game or Greyhawk.