Personally I'd take Ord initially! You will be on reserve for a couple months no matter what, and the crash pad situation is way better and cheaper in Ord! Also, the train is easy to get to and from the airport! Then in the very next vacancy that you're allowed to bid in (there should be one every month for the foreseeable future) switch to MCO or DEN for a line...I would pick Denver (more commutable with red eyes, and lots of movement with upgrades in spring)! Good luck with your choice!

Also DEN is the largest base by FAR, so it has the largest open time pot to switch your schedule around with!