I agree nerite snails are the best. The olive nerites i had seemed to lay 10x more eggs than the tigers and zebras. Horned nerites are good too, mine are much smaller than the others(tigers,zebras,olives) and lay very few eggs. I stay away from apple and ramshorn snails because i read that they will eat certain plants if they do not get enough algae.
aside from keeping a well maintained and balanced system...i am partial to ottos for cleanup myself. i mean i love snails and shrimp, but for some reason they don't last long in my 20L and 8.5g nano... well the i guess the nano doesn't count as i have a voracious pea puffer residing in it lol... but in my 20L i feely water is too soft for the nerites and i have a homicidal (or pescicidal) kuhli loach that loves to snack on shrimp
i guess thats why i'm partial to those little suckers! (literally lol)
Re the comment about nerite snails... Bzzz. You're wrong. I just had some hatch and my water is within normal parameters. It's not true they only hatch in brackish water. I would post a picture if they weren't so tiny.