Favorite sidekick?

[JacobyPAX]

the mags from Phantasy Star online; they can give a huge boost to various stats, sometimes revive you, and release massive amounts of photon energy.

 

[Haunted Serenity]

Bastila, HK-47, I love them.

 

[Rarhnor]

I'll first this:

I think I'll second Daxter.

 

[GuerrillaClock]

Must be Luigi. Come, now. He is the ultimate sidekick in every sense of the word, much as I love 'im.

 

[Vrach]

I'll take party members.

In that case, Thane, Samara and Garrus from ME2 (Thane being the favourite out of the 3 for character value, I love assassins). They're awesome characters, easily effectively controllable and not utterly useless as companions when left to manage themselves.

That's just me though, I've only recently-ish started noticing worthwhile companion characters/sidekicks, they used to be extremely buggy (especially irritating when they'd get stuck and didn't have an unstuck mechanism) and mostly worthless due to terrible "friendly AI" in games.