i been looking alot also
in fact, i don't like the usa because it's pretty expensive compared to brasil ( I'm from across the water, belgium btw)
it's also alot easier to get some money coming in when you're in brasil ( when your purple you could give very cheap privates) you can help people with computer stuff(which is very expensive in brasil etc)
I made my first trip to brasil ( Rio) last summer for a month, and i was hooked really.
there are a few top notch gym's that stand out above all others
Gordo JJ : awesome place & location ( next to the connection rio house) alot of the guys speak english, and there are alot of bigger guys there , if your medio-pesado or up, this will prolly be the BEST shot allround for you. in addition, they also have muay thai, boxing, and MMA classes
Checkmat/Fightzone : this place is crazy, the guys are alot smaller ( i think somewhere between pena & leve is the average weight here!!) and it's more fast paced, and i mean, a hell of a lot more( due to the weight difference). it's in copacabana, litteraly 30 seconds from the beach. it might be harder to find a location here to stay for a longer while, so it's best to come down and ask in the gym after a few sessions ( some guys have a room for free and they will let you stay for a price that can be pretty cheap)
Atos JJ : some of my favorite fighters come out of this camp ( calasans and R. mendes) if you only want to train, and do nothing, nothing, NOTHINGGG else, go here. after 6 months you'll probably be a killing machine in your belt & weight, and also on top of that, speak portuguese very good, since almost nobody speaks it you'll have to learn it. also harder to get a room, but then again the guys from the gym will help you
Alliance : i haven't heard alot from alliance in SP, except that it is amazing to train there. alot of the competitors have moved to the US, but still a load are left there were the champions are made and come from.
Checkmat/Fightzone : gym of leo viera
there are also other big gyms with high reputation, such as cavaca's gym in Santos ( which is also a cheap place to stay), GFT(very old respected team in rio), de la riva in copacabana , BTT, gracie barra HQ and many more
but these are the ones i just know about and heard of
many gyms won't give a crap where you train aslong as you pay your bill( paying for one month varies from 170R$-220R$ depending on gym) but if you plan on staying alot longer ( when you're paying normal prices and fighting), gym politics might be playing part
gym politics might be a difficult choice
for instance, my newer main instructor(who is a great guy) would love that i train at fightzone rio when i go back soon for a very long time where his little cousin trains, while i planned to train mostly at gordo's since it's closer to the connection rio house