I have only tried one but I tried Serena from the Dawnguard DLC and she cannot die so no reloads because follower died. Her virtues are: immortality, for the Dawnguard DLC quest progress, and can carry loot.
Lydia is the best, most beautiful person in the province, and she can be a follower, so she′s naturally the best follower.
But I suppose that if you′re talking stats, not getting in your way and not making clunky noises to warn of your foes, J′zargo and Aela would be best.
I personally found Mjoll to be very useful. Only thing thats bad about her is that she won't equip any bows that you give her. Cicero is also good, but don't choose him if you get easily annoyed by his generic dialogue. Good thing about both of them is that they are essential which means they cannot die.