The 4x4 pede is nice but the summit and emaxx are gonna be much more capable. I would lean towards the summit because the emaxx needs upgrades to be more durable. You could also look at the e-revo. It's the same as the summit but with a different body and lower stance but they include a rocker arm set to increase the ride height to match the summit.
If it was up to me, and you can afford it, I would go with the HPI Savage Flux HP. The newest version is waterproof and it is tougher, and faster than the Traxxas MT's other than the brushless erevo but the brushless erevo isn't waterproof.