The yokomo would probaly be the easiest to get parts for...

Thats the understatement of the year...

Well, why I did not like the X10 is that it is a bit weak and fragile. After one main of hard racing you might end up with a popped out ball stud and damaged steering blocks. At least the yokomo uses aluminum bulkheads and woven carbon fiber which makes it superior to the X10. But the X10 might have lower CG than the yokomo. I'm not sure, though.

Oh, and you go: www.oople.com
Here you'll find some real good reviews on many 2wd and 4wd buggies including the Yokomo and X10.