I haven't ridden the other 2 bikes but obviously I will vouch for the M2R. I received mine a few weeks back and it has surpassed all my expectations of a pit bike after owning a Thumpstar 120 several years back.
TBF, for messing about on they are all the same bike underneath, just with their own manufacturer decals on and the odd different custom part here and there.
As I learned on here when deciding on my bike, pick a price, and pick a colour then enjoy