I take a different approach to water conditioners. I have this thing about adding chemicals/substances that are not absolutely necessary. Any substance added to the water in an aquarium will end up inside the fish. So while this or that may be "safe," it is still entering the fish's bloodstream. This is why fish and their environment are more closely connected than any terrestrial animal.
So with that as my premise, I recommend selecting a water conditioner than does what you need, but no more. And this depends upon the source water (tap or well). And at this point, we are considering "normal" circumstances, not specifically cycling or some problem. For example, if you don't have ammonia, nitrite or nitrate in the source water, then there is no logical reason why you need a conditioner that detoxifies these. This is my beef with Prime. It messes around with processes that should be "natural" and is therefore unnecessary, but more to the point is that it contains chemicals that do this messing around. I also have an issue with the fact that Seachem cannot explain how Prime detoxifies nitrate fully, and that bothers me. Think of it as taking medicine without knowing the side effects.
Another thing to watch out for are substances that really serve no purpose, or may actually be detrimental. Some conditioners contain aloe vera; there is absolutely no evidence of any benefit from this, plus the fact that this sticky goo in the fish's gills may be long-term trouble. Another conditioner contains vallerian; I've no idea why anyone thinks the fish should be drugged to sleep.
Comparing cost is wise, but always include the amount needed. A conditioner that requires 1 ml to treat 1 gallon will need 10 ml for 10 gallons; compare that to those that use 1 ml for 10 gallons. The seemingly lower cost of the first is not much of a savings if any when you need to use 10 times as much. And here again, 10 times more chemical entering the water is less desirable.
I have used Kordons NovAqua (the basic, not the plus) in the past, and for many years. Presently I am using API's Tap Water Conditioner (the basic). Both handle chlorine and chloramine, and heavy metals (I don't need the heavy metals, but I have not found any conditioner that does not detoxify these, except for one or two that I won't use for other reasons like cloudiness). The API is probably the most concentrated product there is; 1 ml treats 20 gallons.
Byron.