Nerite snails are an alternative, though some report issues with them laying rock-hard eggs which don't hatch in freshwater and don't come off things easily!
So far mine have never laid eggs, maybe because I don't have more than one of any type/species of Nerite.
Excellent glass/rock algae cleaners and they have never touched my plants in 6 months, plus they don't get anywhere near as big as some apple snails do, mine are around 1" max.