Since your connection is so long, I'd suggest that having the best lounge access is the way to go. Both airports have Admirals Clubs, but if you have an Amex Plat or Capital One Venture X card, you can go into their respective lounges at DFW, which are both much nicer than Admirals Club Lounges, even if the Amex Centurion lounge is crowded.

Also Chicago routinely has horrendous weather in February, so you may have a higher chance of delays/cancellations through ORD than DFW (although Texas had a pretty rare and unfortunate snowstorm this year).