This is very, very much down to taste and priorities. I played and loved BG1 & 2 when they were first released, and have played them frequently since. I struggled through D:OS on my third attempt and stalled on my first attempt at D:OS2 at the beginning of Act 2, because while I saw much I liked in both games, they somehow didn't grab me. And I love BG3 and think it might end up being my favourite ever game. Knocking either Dragon Age: Origins or Mass Effect (depending what day you ask me) off the top spot, in case that helps calibrate preferences.
In terms of elements of its look and feel, the fact this is made by the same studio as D:OS and D:OS2 is very obvious, though there's a massive step change in things like animation and writing complexity. And the D:OS heritage of elements of the gameplay is also pretty clear, though personally I think the differences from BG1/2 are as much to do with the move to a new version of D&D as to D:OS. And while I love the original BG games, I'm not a huge fan of their combat, and find Larian's turn-based take much more compelling.
It's also complicated by the fact that D:OS and D:OS2 themselves owed a debt to BG1/BG2.
But while I know many people don't see the direct line to BG1/2 in the new game, I do. I particularly see the links to BG1, which despite all the improvements BG2 included, is still the original game I think I have most affection for. That's partly to do with setting, of course, but also elements of the structure and the way we uncover the plot and slowly make our way to Baldur's Gate. And the fact it doesn't take itself too seriously, but you can still play it absolutely straight and have a ripping adventure. Or be silly and have a blast. There are tons of memorable characters and funny lines, as well as lots of moving little stories you can get a glimpse of.
Plus BG3 has a really interesting dynamic that I personally have only really come across in BG1 before (and BG2 to some extent, though I think it's a bit lost by that point) in the sense that it in some ways feels like a Dungeons & Dragons playing simulator rather than (just) a roleplaying game set in a fantasy world. I struggle to explain this, but it's almost as though we aren't playing (or aren't just playing) the fantasy character that we create, but our perspective becomes that of someone playing Dungeons & Dragons with a group of friends with the game coming to life Jumanji-like in front of us. This creates an odd sort of distance between the world and the player that I think some players do find hurts immersion, but I find incredibly interesting and engaging. Though if that doesn't appeal or make any sense, then I'd say the effect is subtle so don't let that put you off!
Which is all a long way of saying that whether you see BG3 as a successor to BG1/BG2 will depend on what you liked about them. Fortunately for me, Larian have picked up on elements that I most appreciated, in some cases quite unconsciously, and created a game that takes those to the next level. Others, as I'm sure you'll find out from other replies in this thread, don't feel the same.
