Well, that's a hard question! The thing to 'Ohanas is that it's Disney, and has a Disney/family friendly feel to it... you know, overlooking the park, family games, etc. We would never choose Texas de Brazil to eat there because we have one here, of course, we tend to try to only do Disney exclusive places while at Disney.
BUT
I think the food selection is wider at Texas de Brazil than 'Ohanas... there are more meats to choose from (though shrimp is not included but is at Ohanas - course the peel is on so its a pain), and I think the steak is better than 'Ohanas, at least when we went. There are more sides to choose from, too, though I ADORE the Ohana sides. It's also less crazy than Ohanas, which is a bit loud, family, activities going on, etc. $38.50 is alot for a regular restaurant back home (price for Dallas location) so it's not as casual, I've found, than 'Ohanas... because the price sorta brings with it more adults... nicer dress... etc. You know?
The presentation is much the same, with the skewers of meat and such, so I think it would be overkill to do both back to back, but on the other hand, my husband LOVED 'Ohanas so much that he could probably eat it two nights in a row. You could always hit one, and if you're really not feeling it the second night, just change dining reservations =)
Hope that helps some!