Both DFW and ORD provide easy domestic connections even with those tight connection times.

There are other considerations (some already mentioned) that would weigh in more for my decision:
1. DFW seems to me more spacious, less crowded and with more natural ight than ORD. It seems to me that at ORD I am always battling my way through (like crossing a street at Times Square).
DFW seems to me a more pleasant experience.
2. Weather. Other than the exceptional snow in DFW, DFW is less likely to be affected by weather in winter.
3. Is the second leg the last flight of the day at either airport? I would lean towards the airport that has more flight options to be re-booked on in case the first flight is late.