I think both cars are awesome. Like mentioned before the associated carries the meanest corner speed I've ever seen has awesome shocks and suspension, the parts are inexpensive too. Every associated 8.2 I've watched and raced against was irritatingly calm, smooth and fast. On the other hand the Mugen simply lasts forever. Very few if any parts need to be replaced very often, and it can be tuned mild to wild in the steering department, and the car always lands on it's feet....
I can over jump anything and the car begs for more. Never broke anything....I can go longer between rebuilds than any buggy I've owned. even then it's just cleaning and replacing bearings.
Both cars are at the top of their game.