If you go by number of episodes and/or number of hours, Jamie beats Sarah Jane (I know because I made a spreadsheet on this a few years ago and posted in this forum). Sorry, minor nitpick.
Hmmm, it might be time to recalculate to take her later appearances with Ten and Eleven into account. And I assume you counted The Two Doctors?
The Borgified Corpse wrote:
Except that, when Troughton died, he was at a convention at the time.
This is true, and I was there at the time (yeah I know, I've told that story before).