personally it all depends on the size of the tank really.
i am assuming that you have a smaller size tank so here i go:
otto cats are good algae eaters as they will only eat algae IME and grow to only 2" MAX most are around 1" or so. they need to be kept in groups preferably 3 or more. Torrean is right about them dieing. they either thrive in a tank or die. there is hardly any middle room. they should be put in a mature, fully cycled tank
rubbernose plecos are good all around clean up crew. they eat algae and even will eat up leftover foods. also they only grow around 5" if i'm not mistaken. (i'm not sure if they are also called bulldog plecos as well- i think buldogs are a different species-not sure bout these 2 as i never kept them)
bristlenose plecos (i know) are awsome clean up crew. they will eat algae very well and eat leftover foods in the tank.
1 snail (don't want it to reproduce)- specifically MTS (malaysian trumpet snails) don't get big at all. they eat leftover foods, detritus, algae and stir up te substrate and loosens sand (if you have it).
common plecos are mediocre algae eaters that do eat leftover foods. be advised that they can get like 18" or larger in size. they are advised ONLY for a LARGE tank
*pretty much don't get any species that is advertised as an "algae eater". i bought one under the assumption that they will be a good algae eater, since their name says they are. well it turned out that it was a CAE (chinese algae eater- which most are) and they only eat algae while they are small (under 5") and will not eat it as much when they are older. they get really aggressive and are just plain EVIL to have in a tank. maybe if i had a large tank i would get one but not until then and it will still be a BIG if.*