Assuming no multiclass and such, very likely Wood Elf Ranger just so I could replace that obnoxious addict Astarion for lockpicks/stealth/sleight of hand proficiency. Prefer this to Rogue as a whole, I don't know if what I see in EA will survive to launch, but you can cheese so hard with ranged attacks and stealth, it's ridiculous.
That's already level 3 Ranger there.
You can basically solo entire temple courtyard like this, by the time they even spot you - you killed half of them, after that you can just run off and hide and keep at it.
And you start with all this level 1 too with Wood Elf Ranger in BG3, they give you 2 proficiencies on top.