Hee! I knew starting_gate would be rushing in here to pipe up! And while I normally think Ben Browder has chemistry with everyone and everything on down to potted plants, I just don't see a Jack/Cam connection. Jack/John in canon I get more of a mentor-y type vibe, but I think they really do connect in an "I totally get you" kind of way. Must be the magic of the ATA gene. ;-)

So I'd vote Jack/John, too, and not just for ^^^ her sake.