I'm thinking the Hyper 8 because its metal and made with quality parts, whereas the E-Revo is more plastic and made with cheap mass-produced parts? But then again i've heard good things about the E-Revo..
I don't have a H8, but I have a hyper st and a 3.3, and the hyper is much stronger out of the box and easier to drive. Less needed upgrades too. The revo isn't bad, but a proper 'uggy is awesome.