There's a lot to be said for being in a room with a casting agent or a director. There are things you can't really replicate when you're self-taping and there's the bonus of having someone to direct you, which is extremely helpful. The benefit of self-taping is, I suppose, being on your own clock. It's certainly more relaxing to self-tape than to audition with someone in the flesh but I don't know if it's necessarily better.