As others have said, DEN is the best choice. It's arguably the best of any major's hub at dealing with snow -- plus it has six LONG runways which can make a difference when aircraft have landing limitations based on runway conditions, braking action, and RVR.

You might think that IAH would be "safe" but the only trip-in-vain I've had due to wx happened at IAH in early December when there was an ice storm.

As to the suggestion that you could drive from DEN, while theoretically possible -- but it's a TEN hour drive -- not five -- in good conditions! If snow has affected DEN and is causing irrops, historically that will usually mean the eastern/southeastern plains of Colorado will be in terrible shape with roads closed -- often if DEN has gotten 10" of snow, the Colorado/Kansas border area will have gotten 20". (And, note, it's actually an hour-and-a-half less to drive to XNA from IAH)