Be sure you understand that no plec "stops" algae. Adding a fish -- any fish -- improves the conditions for the algae, and even an algae-eating fish is going to produce the nitrates and phosphates algae like. If you want a fish (or shrimp, or snail) to put an end to algae, you're out of luck. As
AncientMariner mentions, some species will eat a lot of algae, but you will still need to manually remove it from the front glass, from leaves, and anywhere else a plec can't reach. Really the only sure-fire way to stop algae is to grow plants. I wrote a pinned topic on plecs and algae in the beginners section.
http/www.fishforums.net/index.php?showtopic=135919
Equally important is the fact that most algae-eating catfish actually need a mixed diet including things like bloodworms. Many also need wood, either as dietary fibre to keep them healthy or as an actual food source. But do keep in mind that they have needs and requirements of their own, and typecasting them as algae-eaters/scavengers isn't a good idea.
Plecs are great fish, and I can't imagine having a freshwater aquarium without one. I happen to like Rineloricaria spp. whiptail cats as all-round community tank oddballs; Panaque nigrolineatus as a fairly hardy, colourful jumbo plec; and Otocinclus spp. as all-purpose omnivores in tanks with other small fishes (but nothing big enough they might parasitize).
Cheers,
Neale