Also depends on the temperature and price range you are looking at. I have some rubbernose plecos from PetsMart (do a QT!) that I've had for years in my unheated tanks. In heated and unheated and unplanted tanks, lots of bristlenose. Other small, relatively cheap plecos include, as noted, the clown pleco (L104), L129, etc. Check out PlanetCatfish for a huge catelouge.