Some are better for certain jobs, for example Malaysian Trumpet Snails will aerate the soil in a tank with substrate and dig down into the sand to get at rotting bits of plant matter. And people like Nerite snails because they produce less poop compared to other snails. Ramshorn and Mystery snails are great for algae and dead plant cleanup. But overall, most snails are pretty similar in terms of what you can expect. Some people prefer to buy snails that require a mate of the opposite gender to breed as opposed to a hermaphroditic or asexually reproducing species to keep their snail population stable. Others (like me) really enjoy getting babies :P
If I could pick any snail to go into a breeding tank, I'd probably pick a Nerite snail, since as I mentioned they aren't quite as notorious with their waste production :P Nerites are also quite popular around here, so if you were to get a pair and they produced babies, you could probably sell them to other members.
Last edited by babystarz; 09-22-2012 at 12:30 PM.