If you look at seatguru, the seat pitch on US's A319s, A320s, and A321s is 37 or 38 inches. This is the same seat pitch as the first class seat pitch on DL's 737s, 757s, and A320s, MD80s, and is the same as on United's 737s, 757s, and A-319s.

So if US is "some of the worst in the industry" then both UA and DL are in the same boat on all of their domestic fleets.