They both are not great for cleaning.
Royals have special dietary needs to consider and algae alone will not provide it with what it needs. They are not meant for algae control.
The sail fin will grow fast and start adding huge amounts of waste to your tank. Once they hit a certain size they really don't care for algae they would rather eat prepared fish foods or vegetables ...
People seem to love their BN plecos for algae control. Personally I don't think that's what plecos are meant for.
How bad is the algae that a sponge can't fix?