NO MALAYSIAN TRUMPET SNAILS OR THOSE TINY SNAILS YOU CAN GET FOR FREE. They multiply like crazy even if you only have one. In the snail world, it takes only one to tango.
Are you looking for snail(s) to clean up algae/leftover food, or are you looking for a 'pet'? I consider my apple snail (pomacea bridgesii) a pet, whereas the ramshorns and pond snail are a cleanup crew.
If you don't want your snail(s) to multiply, apple snails are a good choice - unlike many types of snail they do need a male and a female to reproduce (females may lay eggs but they won't hatch if there's no male around to fertilize them). Check out this site if you'd like some more info on apple snails. Keep in mind they can grow to the size of a baseball, so you'll eventually either have to return your snail to a store or get a larger tank to house it; a 10g is just too small. Fortunately they'll grow fairly slowly unless they're very well fed