I had a similar choice to make. Sounds like the drive is a factor, but all else being equal, try to jumpseat a few times and get a sense of cockpit culture and procedure culture.

From my observations, Delta crews had far less callouts and "looser" briefings. United crews had more callouts and briefed off of cards. The PM also seems to take a much more active vs. traditional role at United e.g. setting altitudes, calling "gear up."

Minor things but again, could sway an otherwise equal decision.