Not so fast. I'm going to come in with the other argument (not just for arguments sake, I disagree with the posters above that this is a slam dunk).

There is a big depends on this one.

If you can get a single seat on the E175, I'm taking that all day every day. There is no questions that the A220 is a superior aircraft in every way but if traveling solo, the value of the single seat outweighs the added benefits of the A220.

The only downside is no IFE and DL has now removed streaming IFE so you'll have to download to your laptop/iPad if this is a non-work trip.

Having recently flown the A220 in F on RDU - BOS (~125 miles shorter than JFK - ORD but still under the 900 mile threshold for food), there is no meaningful improvement on either the snack basket or drink offerings between the A220 mainline service and the DL Connection E175 on a flight of this length.

All of that said, if you can't get a single seat on the E175 or you are flying with a companion, take the A220 because it is a superior aircraft vs. the E175 for my own personal preferences, that is always outweighed by the single seat benefit on the E175 (if available)