The savage is a tough one. Not sure if it's any tougher out of the box than associated's MGT, but out of the ones your looking at, it's the top of the pile.
The LST* will out drive it though and still give you the brute power of a big block. It's a bit more fragile. With a few upgrades, can be made tough though.
The revo will more than likely out handle the LST*. It's a very agile rig. However, I'd proffer the LST* over it for it's size and strength (after a few upgrades of course).
If bashing was my only driving force, then savage is what I would buy. The XL is extended over the old savage's and that extra length makes it handle much more gracefully than the shorter ones.
I have had a revo 2.5, 3.3 (chassis) with big block conversion, 18TM and 2.5R. It had enough issues with durability that I gave up on it. I couldn't get it setup in such a way that it would handle well and take big air all day long. I upgraded and adjusted things for over a year. In the end, it would still bend/break on me almost every time out. It would have been a great truck if I had a track to play at. That's where it would really shine. With it's lightness, it was quick, even without a big block in it.
I now have a savage with a 1" extended chassis and a heavily upgraded aftershock. I basically got rid of the revo when I got the aftershock. With a few key upgrades, the aftershock does what I want without damage and still handles pretty good.
I recently traded a 1/8 scale buggy for the savage I have and I have to say, I really enjoy having a savage again. Whenever I run it, the last thing on my mind is fragile.

Usually, the first thing on my mind is "What can I jump this over!". It doesn't handle as well as my aftershock though, but it's still one tough rig. Knowing it's tough is part of what makes it a joy to drive. I don't have to worry about where I run it or how hard I punish it. As long as you have a spare spur, spare shocks and spare axle carriers... your day shouldn't end.