Windrunner: Access to Basic, Full, and Reverse Lashings
Basic Lashing- The most important of the Windrunner's powers in this fight, allows flight.
Full Lashing- Much less usable than Basic Lashings, not used much in arial fights as one with a Skybreaker would be.
Reverse Lashings- Still less useful than Basic Lashings, could be used to block projectiles.
Increased squires- Probably not allowed to have squires in a 1v1 match
Skybreaker- Access to Division and Basic Lashings
Basic Lashing- same as Windrunner
Division- We haven't seen much of Division. We know Dustbringers can burn and engrave things with their powers, but Skybreakers may be different.
Overall, I think that a Skybreaker would win. Full and Reverse Lashings don't really offer much in a fight in the air. Dodging projectiles would be much more efficient than pulling them with a Reverse Lashing, and Full Lashings are very situational. We don't really know what Division does for Skybreakers, but that surge seems more offensive to me than Adhesion. Other than that, assuming equal skill, they are the same. Both have Sprenblades and Shardplate. Both can fly, and both are more combat focused orders, from what we've seen in the books. It comes down to what is more applicable in a 1v1- Division or Adhesion