Personally, divination wizard. It’s very strong in tabletop 5e, and was actually nerfed a decent bit in this game (your portent dice can only be used to replace attack rolls and saving throws, not ability checks, and requires a reaction; in tabletop it actually doesn’t use any action at all). If you’re interested in super optimised builds, I’d actually recommend checking out the various DND 5e class guides and multiclass builds online, for example r/3d6 on Reddit, but bear in mind that various class features might work differently in BG3 or rely on things that only work in a tabletop game