I originally switched from a Losi 8ight to the Xray 808. The 808 is by far the lightest buggy you can get. It's insane. It is easy to push that car very, very hard without upsetting it.
I ended up going to the 8ight 2.0. For some reason they just rotate in the corners much better than anything else. Parts support is amazing, too.
Never tried the Mugen, but if it's anything like their touring car, it's top notch. Seems about equal to Xray.