I've seen the Mugens in person and OMG! They do great. Turn great, jump great, track doesn't mess them up. Good prices too. I have no idea about the other two, but I'm sure you would be pleased with the MBX5T. I also have a friend with the Jammin pro and it does good also, but he seems to break front arms once in a while. Also when he tried using the droop screws on the arms, the diff case would break-or the arms would pull the diff case up off the chassis and strip our where the screws under the chassis hold it. So he quit using the droop screws. But it also handles well.
How is parts support at the LHS's? I'd say that is a big factor. I drive the Losi T and like it a lot.