IMO the T-maxx is a durable truck, however it has weak points in it.
Pros: Parts availability, ease to work on, simplicity.
Cons: plastic bulkheads, plastic, shocks, too much plastic
Revo is cool and all however, (in my LHS) revo parts are semi- hard to come by.
I have an insane amount of money in my maxx however, all I've really broken have been diffs, one set of bulk heads, the body, and the front skid plate. I've cartwheeled my maxx countless times with it just rolling over and asking for more.
I'm really satisfied with my maxx however I wouldnt mind having a revo.
Most of the time, the maxxes you see with all aluminum and all upgrade parts are merely upgrades from stock just to do it. Example, if you break one set of a-arms and you upgrade, you'll probably do all of them or at least both sides, see what i'm getting at here. I do just that when I go to my LHS.
Quality of a MT is relative, it all has to do with what you plan to do with it. Insane jumps, racing, bashing, you decide.