I did the switch to Maya almost 2 years ago and haven't looked back since. That doesn't really mean much though, it's simply because that's what I use at work. They both (all) have some great features - and you'll often find yourself wishing a certain tool from one package was in the other.
I think Z really nailed it though... in terms of approachability Max wins hands down and I'm glad I popped my 3D cherry with it (oh, actually it was TrueSpace 3... but I was just an innocent kid, led astray at the time), I think I would have been overwhelmed and lost wth Maya. But now, having got to a far greater depth in terms of character setup I don't think I'd want to go back to Max and use the wire parameters and reaction manager (I always got a little lost with the wire param thing...)
But at the end of the day it's just a tool. I don't go worrying about the make and model of a hammer when I'm banging in a nail