The MSRP on the Zuk is only 300 bones over a YFZ. It might be cheaper in the long run due to already having the extended a-arms/axle etc. On the other hand it won't be as good for trailriding. Otherwise, they are all going to be similar enough that it really comes down to which manufacturer you feel more comfortable with. Personally, I would go Yamaha as I think their '06 450 is the most rounded package of them all.

 

I don't think it's wise to buy any quad in it's first production year, if major problems turn up down the road, which is likely to happen, you're stuck with the problem.

 

I have a yfz450 and I`m really happy with it
Its faster then I thought it would be