Which one would you like to visit: Brazil or Mexico?

been to both, but my traveling days are over ...............................

Brazil to see Iguazu Falls.

I have been to both. Both are beautiful, geographically diverse countries. Parts of Brazil are far more crime ridden than most of Mexico, despite what people in the US think. It's a shame- but it's what happens when you allow such a huge gap between the rich and the poor. 

 Brazil. Easy choice.

Brazil. A collecting trip up the Amazon would be worth all the red tape I would have to go through.

Nice Islands off the coast of both.. 

Hmm. I kow both Sanish and Portuguese equally as well, but I have been to Mexico - many times  so perhaps Brazil.