1. Benor of Morthal. Why? he is the [censored] terminator, particulary with claymore. Ex. At level 15, I gave him an Orcish claymore (just something i picked up). Then we raided a bandit fort. Benor starting impaling bandits left and right. Every move was an instant kill. He was actually killing them faster than i could ( a dual wielding dragon born ). Later, at level 20 something, in draugr ruins, he owns. Draugr, draugr restless, warlords,. doesn't matter. Once a Draugr warlord, upon immediately rising (rather quickly), used unrelenting shout to push me out of the room. When i returned, Benor had taken a knee, but there were two dead draugr (not the regular draugr either), with three draugr (including warlord ) left. I must note that the warlord was wounded.
2. That guy from Riverwood. Why? good archer, He stays out of your way and apparentyl there is a glitch to recieve archery training, then pickpocket it out of him.
3. Lydia from Whiterun. Why? it's nice to have a female on those lonely journeys

Benor is the Boon of Skyrim
what say you?