The serpent, all the way.
I had a mugen buggy and a serpent onroad; the serpent is ticking like a swiss watch. it's unbelievable precise made.
I don't know is this forum gives you an uncoulored pol though, since most of the crowd only know Mugen for their buggies, and don't know serpent at all.
http://www.serpent.com/product/903008
this is the 08 serpent.
Simple look at the rear sway-bar of the serpent; it's using bearings, and it's made of the flat bars, which can be adjusted fair easy. the upper front arm bulk; well machined aluminum; the center drive-thingy (where the two belts come together) that's aluminum too, if they sell it for the same price (like they do) i would take the serpent without a doubt.