The best food for "pleco" is one that closely replicates what ever the particular species of pleco you are keeping would eat in nature, be that algae, meat, wood, etc etc.
I feed my plecos algae wafers and then some shrimp pellets to get meat and veg in their diet. I also make sure i have driftwood in my tank it is healthy for some of them to rasp off of.
I just introducing gd old hikari veggie wafers..much to my surprise I think this is they're new favorite, even my more meat eating plecs like my L600 & L273 go nuts over them. They're obviously super healthy too..PE mysis has always been one of my fav foods to give them as well