I think shrimp are better cleaners. They will eat anything including dead fish. Cory's are good little scavangers, they go around and play on the bottom and do a good job of stirring stuff up so that the power filter can get it, but when it comes to eating, sometimes they just swim along with your fish and eat the food right from the top (or middle) of the tank. Pletco's are better scavengers, they will eat algae too. But they do get big and poop alot. just my 2 cents. Go with the Shrimp id say. Or get them all. haha