In my opinion, to take your point further, Animation Master or Hash is a prime example, then, to take it even further, there's Gimp.
Combustion is a good package, more expensive than AE and Commotion put together these days but then I started on Commotion when it's price was no small potatoes either so I never really got the benefit of the price drop. Bottom line is it's pretty much down to preference, so I hold to the advice 'Go see them in action' and pick the one that clicks with you.
