I've used both Movie Magic and Final Draft. I own Movie Magic. It seems a little more intuitive to me. When I used FD, it didn't export to PDF. MMS also updates automatically. When I went from Mac OS 9 to OSX, didn't cost me anything to update it and the update was just a download. There was a version of Final Draft that had some serious bugs in it (vers. 7?)
But yeah, when you you spend your money on something like this, it gets a little religious-like.