For overall, the best type is the Mexican turbo snail. I would recommend two or three of them for a 14 gallon.
However, you are best suited by getting a wide variety of species because each species will serve you differently by eating different types of algae (brown, green, diatom, cyanobacteria, hair algae, macro) and at different locations (glass, rocks, sandbed).
Get some nassarius snails (~5), astrea snails (~5), cerith snails(~5), in addition to a few Mexican turbo snails (2-3).
:joy: