There is a great documentary film, with the simplist of titles: Jimi Hendrix. Can't find it on youtube. Last saw it in 1986, it was so good I went back and saw it the next night.
Interviews with family friends peers, and live footage.
I can also recommend watching any of the bits from the Monterey Pop festival. They are fantastic.
The best? who knows. It's personal. Depends on the listener.
I like Hubert Sumlin, played with both Howlin Wolf and Muddy Waters.
Poison Ivy, the cramps.
And of course, Jerry Garcia. Again, Garcia had many mediocre nights, but when he was on... OMG!!!! Fantastic.
And how about that nutty girl in St. Vincent?