I am a fan of NovAqua. The new formula seems to be working quite nicely.. The problem I see with Prime/AmQuel is that if you chemically bind Ammonia before it can be broken down by the nitrogen cycle, then you are 'starving' your biological filtration, which will weaken it. If you have Chloramine in your water however, these chemicals are a must. Most other conditioners will remove heavy metals as well..
Any water conditioner that is Aloe Vera based is crap.. First off, fish don't need aloe vera to replace slime coat.. Most water conditioners will do this, as well as Aquarium salt. I have read on many accounts that an overdose of an aloe vera based conditioner can cause the aloe vera to build up in the gill function of the fish, causing them to sufficate..