The Cowboys are the more well-rounded team with far better skill position talent than the Bears. Dak Prescott and Ezekiel Elliot rate major edges on Mitch Trubisky and David Montgomery. 
The Bears haven't recovered from their London loss to the Raiders. They are 3-5 in their last eight games with their lone victories during this span coming against the Giants and Lions twice. Those teams have a combined record of 5-18. Trubisky has only played well against the Lions. He's been a stiff against every other opponent. 
Chicago's defense is down from last season and its offense has been hijacked by Trubisky's lack of progress. Chicago's run defense is prey to Elliott likley missing run-stuffing Akiem Hicks and linebacker Danny Trevathan. 
The Cowboys are the more motivated team. Dallas is that rare team that rates high in both offensive and defensive yards. The Cowboys average the most yards per game in the NFL and they surrender the eighth-fewest yards.