We were told that the Brazil side was "better" has it offered the best views of the falls. After a brief decision we headed to the Argentina side to do a comparison. And basically, there is no comparison, Argentina wins hands down.
Apart from having an equally good view (probably better) of the falls, they had a much better railing system (we were not so crowded), much longer and many more walks through forests, better eating areas, trains and lots and lots of Coatis.
For a slightly lower price as well, if anyone is thinking of going, just go to the Argentine side, its better.