The best race for every class is the one you want to play.
Want to play a human? Go for it. Want a duergar? Go for it.
It's a RPG, not an EXCEL spreadsheet... there's no need to play an optimized race.
No, according to Larian you are playing wrong. You must play what maxes your combat power. Thats why they changed the ASI as otherwise you would be physically unable to play anything except the best race/class combinations.
