I have never seen the tnx or revo run in the flesh, only on vids. but i would go for the TNX for the following reason..

the revo is a brand new truck, sure it has a load of R+D on it but it is still first gen.

the TNX is basicly a second gen Terra Crusher, so it has had more chance to be polished and fettled....

I think I would rather own a revo, but the tnx seems like a better bet....

also tamiya are probably the biggest manufacturer in RC, they have a reputation for building tougher than hell models that put up with beginner abuse very happily.... Traxxas have a reputation for making their models out of glass....