The Granite Mega is a good choice, but for parts support and local hobby shop ease of access, it makes the Traxxas the better choice.

That being said...

Frankly, the Arrma is a better rig that’s better built. I own two of both and one of the Arrma’s has a castle sensored system in it that runs 3s all the time. While I’ve had problems with the front shocks shafts breaking, that’s about it.

The Traxxas...well, that’s another story. I’ve had repeated issues both of those, from driveshafts, to steering knuckles, to burn up motors...they haven’t been reliable whereas my Arrma’s are.

If they made the “mega” version using the same HD parts as the 4s Kraton and Outcast, it would be the clear choice.

My 2 cents.