Apple or mystery snails are popular, but poop more than they eat. A nerite is a better option, they are not as large, do not eat live plants, and do not reproduce.
Shrimp are your only other option, but are often snacks. Ghost are common, inexpensive, and depending on being true thosts may be aggressive. Red cherries are colorful, small, and prone to breeding prolifically. Amano shrimp are mid size between the two, and eaymt algae, nay need to have their diet supplemented.
Any other shrimp will likely be unavailable, unsuitable, or just too expensive. Remember, nothing is a substitute for cleaning yourself.