As for a chlorine/chloramine remover, I compare the $/gallons treated - same as you would do at the grocery store. As long as the product removes the right thing (chlorine and chloramine are two different chemicals used to disinfect water), it is only a matter of how dilute the solution in the bottle. In my part of the US, Prime seems to be the most economical - 1 capful (5ml) treats up to 50 US gallons. The cost is not much more than the same size bottle of the competitors, but the competitors require more volume per 50 gallons - so it has a higher cost per dose.
72g bowfront planted, CO2, 4x - T5HO, Eheim 2213 and 2217, 2 angels, pristella tetras, blue tetras, betta, albino bristlenose pleco, albino cories. Sword, vals, hygros, ludwigias, java moss and fern, anubias
2g Mac-quarium. Clown gravel, fluorescent plastic plants, and 2 guppies.