Both seats are slightly narrower then the 772s -- maybe an inch
You have window views on the 763
787-10 is a bit quieter and pressurized for a lower altitude. Some feel you are less jag lagged as a result
This may help
Everything You Want to Know About Where to Sit on a 767-300 (30/46/138)- Polaris seat - FlyerTalk Forums
Everything you want to know about where to sit on the 787-10 - FlyerTalk Forums
I prefer the longer TATL which would be an advantage for ORD
In April, neither airport has a weather delay advantage
International connections -- it can be OK or bad at either airport depending on the other arrivals. Assuming the train is finally back by April at ORD, it is a toss up on my mind, EWR might have a small edge
Note the aircraft used in April 2022 may not be the aircraft you are booking, Aircraft assignment can/do change and schedules can change
Is height or footwell size an issue?