I'm just gonna respond to the 'Does Sarevok make for a good villain' thing
Sarevok has, in BG1, about as much attention as Ketheric Thorm in BG3. He is, more or less what Gortash should have been.
Agreed, there's only a handful of scenes, but a lot of notes, letters and diaries and references to what he has been up to. The major difference between Sarevok and any of the villains in BG3 -
There is no personal motive in BG3. Whereas the deal with Sarevok is, right from the get-go: "You killed my father, prepare to die."
Right after you meet him past the tutorial. He murdered your father, that set you on a path. You're all alone, you can't go back, but your friend is with you, and Dad told you where to find more friends - You're perfectly free to now roam the world as you see fit, be that adventurer that you will grow to be. But, that 'Armored Figure' is your enemy, that confrontation is assured and you'll learn more about him as you travel. You'll quickly recognise the assassins in Candlekeep, and others you'll come across along your journey were on his payroll. You're directly opposing each other from the prologue to the end.
In BG3, there is no such goal. You're off to find a healer. Okay. Then, you come across the Emerald Enclave and the Tieflings. They have a struggle of sorts, and they send you to find that healer in Absolute-Adventure-Land. All fine, but you have no quarrel with the Absolute nor their men. That quarrel may very well arise, but your goal is to find a cure for something seemingly unrelated. As for regular-Tav, anyway, there is no personal stake, grudge or anything like that with anyone in the whole game. And, for everyone else that can be the protagonist - except Karlach - no one has a personal stake with anyone within the Absolute's forces. Lae'Zel can *get* to that point, but again - the Absolute is just an obstacle, not a personal gripe. Worst of all, your goal of that cure goes out the window at some point. You can still mention it her and there, but no one is still looking. They're all on board with what you're doing, but you have no clear goal, no antagonist, no stake in this story.
