The older Obi Wan Kenobi or Qui-Gon Jinn?  

I'd have to go with Qui-Gon Jinn for a mentor out of that choice. You didn't really see much of Obi Wan teaching Luke or anyone else for that matter. Qui-Gon there was a lot more shown of him teaching the young Obi Wan, arguing with the council, and even teaching young Annikan.

Obi Wan is clearly the better mentor because he is the poster boy for all Jedi in that he follows all the rules, teachings, and he is completely balanced.

On the other hand, Qui-Gon is the anti-Jedi. He cares only for the "Living Force" and constantly goes against the Jedi teachings. Face it, Qui-Gon did not do that much teaching in regards to Obi-Wan other than the stuff he taught after he died. Obi-Wan was actually taught more by Anakin.

Thats a hard choice cause i myself liked qui-gon jinn better but obi wan kenobi was more of the movies.But anakin did go vader under obi wan's teaching so maybe he was not such a good mentor.

The older Obi Wan Kenobi!
How can we forget Sir Alec Guinness
and his own "Ben" Kenobi.

Qui-Gon Jinn of course. The older Obi Wan you only saw in the first Star wars movie. In it he didn't spend much time training him anyway.

I think it has to be Qui-Gon Jinn. He was Obi Wan's master and obviously trained him well. Episode I showed him as a great Jedi master. Obi Wan is a top Jedi and has therefore been taught to a very high standard by Qui-Gon. Qui-Gon is the best jedi and deserves this title!

Qui gon Jin, I loved him. He was a real Jedi, very patient and all and fighted a lot. But the difference is really small, I love Obi Wan.