aiight here we go...
they're different kinds of trucks. I have a decently modded Nitro MT (check my profile for my website). I would recommend the MT simply cause it's 4wd. it might not be as fast, cause it's 4wd, but it's well worth having the extra traction. I actually ran my MT in rwd, and, after driving it around in 4wd for like a year, the drop in traction was almost inhibiting...although, with my onroad tires I did appreciate the fact that I could do endless (if i wanted to) donuts. but anyway, the rush would be good if you want nice top-end speed with a simple, relatively cheap (a bit cheaper than the MT) truck. if you're willing to put out the extra cash, I would definitely go with the MT. it also depends on whether you're gonna be doing more on or off roading. if it's more off-roading, you're gonna want to go with the MT. with me, with those giant tires you'd see in my pics, I haven't been able to loose control (because of traction) while off-roading. with the rush, especially if you decide to get a more powerful engine, off-roading could get a bit tiresome. if you decide you're gonna want a good mix of on and off roading, sure you could get the rush, but the MT would also be a good option, cause all you need is like 8 bux for some stiff springs, lower the suspension settings, and you're set. that's what I do, but I have a set of on-road tires. also, you can get a 2-speed or a slipper clutch for the MT, whereas the rush is only available (and comes standard with) the slipper clutch.
hah, sorry for all my rambling on, but the bottom line is that the MT is better....in my opinion. if you want more info, in terms of features and hop-ups, about one of the two, ask away!
hoped this helped somewhat