I think the best answer is none of the above. Controlling excess phosphates is the best way to control hair algae. Micro hermits are good, but you are treating the symptoms, not the disease. The cause of haie algae is nutrients, especially nitrates and phosphates. I chased hair algae with herbivores for years without a lot of success. It would just come back after the snails and hermits died back. I'm not saying that herbivores aren't important, but rather its just part of the puzzle. Rather than go with just one herbivore, I would suggest a package. If they are going in with your predators that might be a problem though. I started off with the GARF (www.garf.org) janitors. A lot of people have since copied their cleanup crews such as Reeftopia. The GARF crew is a mixture of Mexican micro red leg hermits, nerite snails, and cerith snails. That was the best general purpose clean up crew I ever saw.
Gary
125 SPS, 75 gal. LPS/softie reef, 9 gal. Nano