I'm still going through The Witcher 3 right now but I'm debating between whether to get Diablo 4 or BG 3 next once I'm done. I was thinking of Starfield as well but I've heard that it was pretty buggy as well.
BG3 is, thus far, fantastic. And it seems to be improving with each new patch.
It's reactive and generally pretty immersive. The gameplay mostly improves on D&D 5th Edition rules (with a few exceptions, I'd say, but you can mod that). It's ENORMOUS. I have probably about 80 hours in my current playthru. (My total time is something like 230 hours, but that includes the roughly 90 I put in on early access, and the time where I leave the game on while I go eat dinner or whatever.) Now, granted, a lot of that is stuff like inventory management because I'm a "vendor trash vacuum." (Which actually does pay off in this game.) And some of it is also me exploring different responses in conversations and save-scumming (No, I won't apologize for it. I play how I like, thankyouverymuch.) And I'm only about halfway thru.
There seems to be a ton of replay value depending on how you want to approach relationships and quests, and there are some quests and relationships which lock out others.
It's not perfect, though. It apparently does require an SSD (like, an actual M2 style SSD, not just a solid-state SATA, although that's at least better than an HDD). I have one and I haven't noticed huge slowdowns yet now that I've gotten to the more populated part of the game.
The voice acting is generally excellent, the story is fun and interesting -- doubly so if you know your D&D lore. There are a bunch of class-specific dialogue options that really do make a difference in how things proceed.
I'll give you an example. There's a part where you are confronted by a minion of Hell who poses a serious threat to you along with the small squad of infernal badguys he's commanding. He's bound by a contract. You can fight him, you can offer to try to get him out of his contract in a way that will piss off a companion of yours, OR if you are persuasive enough, you can talk your way thru the fight by actually getting him to kill himself and his minions! And you get the same XP for resolving it either way you do it.
There are things I wish were in the game and improvements I wish they'd make, but on the whole I'm really happy with it.
For D4, I've heard mixed things. I've never been a Diablo fan at a baseline, but I've heard some friends who love the gameplay. At the same time, I've heard it has a bunch of microtransactions in it? Dunno if that's optional or what, or if you care about it.
Starfield I'll get around to eventually but...first I actually have to play fallout: New Vegas and Fallout 4.
