My Yellow Tang blew through an outbreak of of Bryopsis a long time ago. You can usually find them for cheap too... I think I only paid $20 or $30 for him from the LFS.
I had a Tomini, Powder Blue, and Yellow... and my display was algae free. They pretty much grazed on the rocks 24/7.
Purple Tangs are also supposed to go nuts on algae, but they cost significantly more.
IMO you'd be best served going with a Yellow Tang or Foxface Rabbitfish. People seem to have the most luck with them, and they usually don't cost that much.