I like the tricks they do in BMX, that's where mountain biking is totally blown away. However, you can go a LOT bigger on mountain bikes, I have yet to see a BMX kid drop a 30 foot cliff, backflip a 40 foot table, oor do 60 mph down a gnarly trail. Of course I'll like MTB better cause that's what I do, but BMX is awesome in many ways as well.