So far Union in the last couple years has not impressed me. The 390's are a great do everything binding. M9's will be the most comfortable and provide better edge to edge performance, but not the best dampening. The Nationals have Harshmellow which in my opinion is second only to Raiden Airbags, and the urethane backs will give you enough support to satisfy but plenty of tweak in the park. Which if you wanna go with airbags you might like Zero's, but you might find them a little to soft for your board choices. Actually they'd do pretty well.
Changed my mind, get Zero's. When I was going to get a Blacklist I was planning on putting Zero's on it. Airbags are the shiznat and the highback is just enough for what I like in a binding. Skatey feel.