I like to stay at tables, where I have been winning. Maybe its a sign, the table is good, and if nothing else it matters psycologically to sit with a big stack. Often other players will tend to stay out of the way of the chip leader a little bit, because they mistakenly think, he is very good or always gets lucky.
I dont like to risk more than 5% of my bankroll on a single hand though. So if someone else is deep as well, and I have to much at risk against him, that is a legit reason to leave. Especially if he is a good player and on my left. I might also leave, if I am up, because I busted the only bad player at the table, and he then left.