Neither for me. One is currently a great assistant coach who has failed as a head coach, the other looks to have the potential to be a very good coach but is still green.
If it has to be one, I guess Fisher, the great assistant coach.
My issue with Fisher is that he has been a head coach before and failed fairly badly. I don't know if he has changed. The impression I got was that he realised that he is better as an assistant coach than a head coach, but I could be completely wrong (as I said, that was my impression).
Larkham, well, he needs more time. Looks to have potential, but I don't see him as the head coach type yet, not with his dearth of coaching experience.