I have a Bristlenose Pleco in my 10 gallon anti-algae tank as per my signature. I don't know what the heck he eats cause he does not get fed a lot and it isn't the plants. He has not harmed any of the plants even the most delicate and I am currently thinking of replacing the SAE that passed away in my 40 gallon tank with an Bristlenose Pleco.
I had a clown loach and pakistani(aka:yo-yo) loach in my 40 gallon. At that time it was an unplanted tank with plastic tanks. Thank God as those two SOBS would uproot any live plants I placed in the tank. The Pakistani Loach pretty much chewed around the stems of my anubias and I could not keep any live plants in the tank when he was alive. They both passed away after 6 years and I never replaced them as I planned to convert my 40 gallon to a live plant tank and did not want to risk having these guys uproot my plants.
I have mini ramshorns snails in my 40 gallon and if they do eat algae, they don't appear to be making much of a dent in the problem.
I had a black molly that I bought when I gave away a monsterous Severum Cichlid and Firemouth Cichlid that grew too big for my 20 gallon and decided to convert the tank into a community tank with different fish. At the time, the tank was over run with green dust algae and diatoms that were just in the end stages and the GDA was beginning to peel off in layers. I bought otos and the molly for starters and the molly kept pecking away at the layers of algae non-stop and totally devoured it. Much to my shock, she was pregnant and gave birth to 18 fry

Not something I ever expected or was prepared for. Unless you don't mind a lot of baby mollies, you may want to try and get a male molly instead of a female molly as the female molly may be expecting. I read that once a female molly is impregnated it can give numerous fry over many.....many.....times without getting impregnated again.
For snail control, you may want to look at a Talking Catfish(AKA: Raphael cat fish). They are known to eat snails whole and poop out the shells and are not known to damage plants. Nerite snails are known to eat all kinds of algae including the types that other snails or algae eaters will not eat such as Blue Green Algae and Green Spot Algae. The only thing is that they have a tendency to unrelentlessly lay eggs which don't hatch but will litter your aquarium with what looks like salt crystals.
For algae control, depending on what kind of algae you have, a bristlenose pleco and ottos may serve you well. As far as Siamese Algae eaters go, my algae eater was quite the algae eater when he was a young whipper snapper. As he got older, he seemed to eat less algae, even when he was not fed and spent most of his time hiding.