RO water is actually dangerous for FW tanks. I had no buffering capacity, so fish wastes will rapidly acidify it, and anything that dissolves into the water that hardens it will correspondingly rapidly raise the PH. Either of these could cause rapid deadly PH swings. Additionally, trace minerals and trace salts which are present in regular tap water and are useful to fish are absent in RO water. Unless your local water quality is useless garbage, it is also a waste of money, though.
Prime - good chlorine and chloramine treatment. Also detoxifies nitrites in a cycling aquarium. Good stuff.
Aquasafe and stress coat - they treat for chlorine, but stress coat does not actually detoxify ammonia in chloramines, just unbinds the chloramine bond so the biofilter can take care of it the ammonia. Aquasafe actualy does neutralize the ammonia as well. I won't use either because they have slime coat enhancers in them, and I dislike treating for things my fish don't need. They also add organic slime to the tank, which rots eventually, especially the aloe in the stress coat. The aloe also gunks up carbon, purigen, and other resins.
http://www.thetropicaltank.co.uk/rev-cond.htm
here is more detailed information on the most common conditioners.
No matter how magnificent your successes or devastating your failures, the worlds' approximately 5 billion impoverished people could not possibly care less.
