I did a quick check to compare personal seating space on various aircraft between Delta and CO. They're all fairly comparable with two exceptions. One, Delta has 60" pitch in business on their 767s and 777s vs 55" for CO on 757s, 767s, and 777s. And two, Delta has 2-2-2 seating in business on their 767s vs. 2-1-2 for CO resulting in substantially narrower seats on Delta's 767s than on CO's 757s and 767.

The one thing that Delta may have going for them over CO's 757s is if they have personal entertainment on their 767s and 777s in coach. Do they?