I prefer stomatellas since they cause few problems and maintain their numbers in your tank. Their population increases or decreases based on need and predation. However, most people don't comercially sell them for some very odd reason. Maybe they aren't pretty enough.
Of the easy to find snails, nerites and ceriths won't damage your rock work or move too many things around uneccesarily. Neither one of those gets very big, and you can find plenty of smaller dwarf ceriths around in people's tanks that are shipped in from Florida.
One of Reef Frontier's sponsors, reeflcleaners.org sells these at super reasonable prices. Make sure to check for blue legs though, seems like one always rides along with your order. :yo: