I voted for 1: The good ending is miserable and could be improved with small twaeks
For me that would be:
- having Omeluum there, if he lives
- having the Emperor and Orpheus work together and have them come to blows afterwards.
- For Karlach: have her ending solved (either joing her or have Wyll join her, if he stays the Blade), before you decide what you do with your potential love interest, for example going with Lae'zel fighting Vlaakith, so that she doesn't automatically die.
- Spawn Astarion I think gets a betetr reaction already
Or let Gortash live and he is the one, that becomes a mindflayer, but I think, getting Jason Isaacs for more lines would be hard. SO I wouldn't call it a tweak.