It's going to be a horse race alright. The more I think about it though, the more I think it'll go to Colorado - specifically Colorado Springs and what is currently Schriever Air Force Base. Consider:
- Space Force will grow out of current Air Force assets and units
- SAFB and the 50th Space Wing are currently doing several of the missions that Space Force will no-doubt be tasked to perform
- The Air Force knows it will lose SAFB to the Space Force, there is no plausible scenario where they keep it, this includes the mission(s), assets, and probably many of the personnel (civilian and military) who work at SAFB or who have rotated through there
- In other words SAFB might make a good sacrifice from an Air Force perspective, something they are going to have to give up anyway - while protecting other bigger bases, from having to co-locate and share to outright losing control of them
- Space Force, when not actually in space will be communicating to space assets via satellite control etc. - well SAFB is one of if not the largest Air Force Space Command satellite control nodes
- The Colorado Springs area has a relatively low cost of living, certainly lower than anything in CA and probably lower than anything in FL, though TX may have it beat - it is still a fairly easy sell to get people to move once people see how nice it is
- Colorado Springs is a military friendly town, with Peterson Air Force Base, Cheyenne Mountain/USNORTHCOM/NORAD, the Air Force Academy, and Fort Carson
- Having those other service branches present is important, Space Force will need to coordinate with the other branches
- There's even a small Navy presence washed up on the Rockies thanks to the Missile Defense Agency activity at SAFB
- The MDA has a fairly significant presence on SAFB as a tenant activity
- MDA will either be working closely with the Space Force or perhaps even pulled into it
- All the major defense contractors have a presence in Colorado Springs or at one of the bases
- There is room to grow as SAFB is out in the middle of nowhere a few miles east of the Springs.
- Politically it makes sense, Colorado is a red state held hostage by the very blue Denver/Boulder area - bringing in more military and civilian defense workers who tend to lean right might tip the state back
In short, all the President has to do is change the name on the sign at the gate and maybe on a couple of buildings and he could have a near instant start-up of Space Force.