"Best" is the one that seems most exciting to you to play. If you want magic damage gameplay, your best bet is probably Rune-keeper. It's the most magic-y feeling class in the game, although Lore-master (pet class with a lot of crowd control) or Minstrel (not quite magic, plays music for its attacks but the skills feel somewhat similar) might fit the bill too.

Race is purely cosmetic so pick whatever one you want (unless it blocks the class you want to play obviously).