Mario's Bbq is definitely a solid choice for Portuguese chicken. Obviously, I can't help but compare it to Brasas. I think the chicken is pretty close but Brasas' chicken wins, as it is better seasoned in my opinion. That's not to say that there's something wrong with Mario's chicken. Just a personal preference, I suppose.
In all other aspects, Mario's Bbq wins. There are far better choices for side dishes. Portions are more generous. The service is great - very friendly, chatty, smiles everywhere (so, like, total opposite of Brasas). The prices are better. Location is more convenient - right in the middle of Mississauga (totally depends where you live though).
I highly recommend it. I'll be back there soon!