A Witchhunter! The "spellbow" of the lot. Melee in Morrowind was awful, in my opinion (especially at low skill levels), and there's more to be desired from the melee in Oblivion and Skyrim, though the latter is definitely much better than the former. At any rate, I never particularly enjoyed focusing on melee in any of the games, whilst ranged combat has been a staple for me. Besides, in an open world, engaging enemies at a distance is usually better than getting up close. So bows for me.
And magic: because it's too useful to stay away from.