Your issue is not so much weather in Austin or Orlando, but weather whereever your flight is originating from.
Lets say you are booked for a flight departing Austin at 3:00pm. That plane isn't just sitting at the airport all day waiting for the 3:00 pm flight. It's coming from somewhere. So if it's coming from somewhere easily affected by weather, it won't make a bees knees of difference if it's 80 and sunny in Austin and Orlando, and everywhere in between for that matter.
If it were me, I'd choose CO through HOU, first flight out in the am. My next choice would be DL through DFW, again, first flight out. The equipment for the first flight out of any airport to a hub has almost always been grounded over night, so it will be waiting there freshly serviced and ready to rock in the am. Also the crew will either be locally based or will have overnighted locally, so you wo'nt need to worry about that part of the problem. (I've been on as many flights delayed due to crew delays as I have due to equipment delays.)
Anne