Freedom seems a bit strong and has the best synergies with all the specialist oriented tenets, but I think Order will actually be better for a space victory. As Calouste said, tech is more important than production for a space victory and Worker Faculties basically gives your whole civ a 25% research boost if you don't have any puppets, and my guess is that Five-Year Plan will do more for your spaceship production that Space Procurement. I also believe that the true strength of Spaceflight Pioneers doesn't lie in the ability to rush with GEs but rather in the 10
in the capital (most likely before modifiers) which can be a big deal for tall empires.
And since I mentioned synergies: Commerce tree + Big Ben + Skycrapers could mean that an Order civ in the late game will be able to
buy most of the expensive buildings and focus production on wonder spamming.
The only thing I don't like about Order is that it has the most obviously useless tenet we know: Resettlement. Who founds new cities in late Industrial/Modern ? It's even tier 2 so there'S virtually no way to get it while it could be useful. I hope this gets changed before or after release to something boosting internal trade routes oe just a growth bonus for your smallest cities.