Oto's need more room than a 10 gallon offers. PLus since they are schooling fish and do such a good job at algea eating, they'll run through the 10 gallon's algea faster than it will be able to grow it for them to eat. I'd cross that out.
My suggestion is for Nerites/mystery snails and/or amano shrimp. both of those guys do a great job at it.