Having owned two E-maxx's and two Stampedes I think I can answer this.
The E-maxx is large, heavy, fragile in stock form, and basically a money pit. I have additional hundreds into mine and I still consider it fragile even after RPM shock towers, arms, knuckles, aluminum skids, bulks, lower chassis braces, and Ti hingepins. That said, when it isn't broken it drives fairly well, although the stock steering servos bringith the suck, and tears stuff up. Even though it has good flex, it doesn't do true offroading due to limited chassis clearence (really the pede has better usable ground clearance).
The stampede is light, agile, very durable, and basically just tons of fun. It unquestionable jumps better than a Maxx, having a better weight/suspension travel ratio. The high CG design seems odd, but it ussally lands on it's wheels after wrecks and almost always jumps true and level. I've had one for years and still think its a blast.
In retro spect, I'd much rather have an E-revo than an E-maxx. Revo has much better suspension geometry, bulkhead design, chassis setup, and overall durability.
If you really need 4wd get a Revo, but if you can tolerate 2wd purchase the stampede. Truck for the dollar I believe you end up farther ahead in the long run.