I've had experience with all but the Xmaxx. That's out of our price range at the moment. Why would you want the 4WD Stampede if you already own the first version? It was a horrible design from the get go. Can't believe it's still being used. It's high center of gravity made it super tippy. Maybe you like chasing it down and flipping it over. In my circle of family and friends, there's at least 3 sitting on shelves. Waste of money.
The Emaxx is just a better version of the Stampede. Still has a high COG and tips a lot. But....it can take a beating. Designed well, and with a few upgrades, you can hand the remote to a 3 year old. We've done it. There's 3 Emaxx's and 2 Tmaxx 's in our group. All are the first generation. Updated, of course, but still being used.
I would highly suggest the Erevo. Light years ahead in design. Low COG keeps it upright, and can handle almost any terrain. We have 2 full sized Revos, 2 mini Revos and now a mini Summit. (Same thing).
I'm not bashing on Traxxas. They're great entry level RCs. But you have to spend just as much in hop-ups to