Daemontools has never let me down. It plays nicely with the OS in that I don't have to muck around with essential system daemons and init scripts, and it corrects all sorts of bad behavior. I run everything with it: python, java (including long-running servers), ruby, perl... Really a fantastic package.
I think it's a question of which tool you learn first. You learn one, it solves your problems and the rest does it differently, so they're "wrong" or difficult in your eyes.
