Kingmaker was a train-wreck for its own reasons-basically the last half of that game was minimally finished and involved constant grind fights. Felt awful. It's probably the best comparison for BG 1/2 strictly, but probably the throne of bhaal expansion-easily the weakest.

Now, BG3 itself is obviously not the same game, or even type of game. I won't deny that you could easily argue that they should have called it something else-it shares minimal story elements, gameplay elements, aesthetic elements, etc. I don't really mind, and don't think "successor" is a meaningful title. Each game is it's own thing.

PoE is probably the most aesthetically, gameplay, and even (in it's own way) storyline similar game-the problem with PoE is that the game kinduve slowed down for me by the end, and just felt...not great, really. I kinduve lost steam at the finish line and never entered into the final act. Haven't even opened POE 2 because I never finished POE 1. Maybe that's just me, but it lost draw for some reason. Maybe it was, honestly, just too complicated?

Of the more recent games-even PoE is slightly older now-I'd point to Solasta as the best example of what a turn-based successor to the old school DnD games would be. I mostly feel icewind dale in it-no companions, build your own party, but still has a storyline. I feel like Solasta is much shallower in terms of story interaction, but much tighter in terms of gameplay and rule implementation.

Personally, I feel that BG3 would be significantly better if they could fix the glaring, massive issues with the DnD 5e implementation, but it will never feel the same...Which is fine, it can still be an engaging game.