There are so many. John K., btcrow, bitmit. Anyone who both me and the other party agrees is trustworthy.
There is a list of forum escrow providers:
https://bitcointalk.org/index.php?topic=108716.0As far as I know, there have been no unresolved complaints about anyone on that list. That being said, I think the only three who have enough reputation that I'd use them for a large transaction are:
gweedo
Graet
John K.
and of course I'd trust myself