I'm on about 20 CE sectors and about 20 EZY sectors this year, so hopefully in a fairly decent position to make a comparison. This is from the perspective of a BA silver member and an EZY plus cardholder with Priority Pass when needed for lounge access.

Boarding: EZY win. Speedy boarding is simple, enforced across the network, and there are no issues with cabin baggage. My main bugbear is being called to the gate miles too early and standing in a queue for no reason, though in fairness their turnarounds are usually pretty rapid.
Ground experience: Slight BA win, though closer than expected. Clearly the overall BA lounge offering though not always ideal is better. But EZY plus comes with priority security at quite a lot of airports now and Priority Pass is working better than it did a year ago.
Seats: Clear BA win. I find the EZY seat becomes pretty uncomfortable on legs over about 90 minutes or so. The headrest and general comfort is a big plus for BA. As is the empty middle seat (though I seem to get that quite often with EZY recently too).
Punctuality: Tie. Neither airline is great on that front at the moment.
Food: Clear BA win in CE. I find the offering pretty impressive to be honest and a lot better than other European short-haul operators. EZY don't have much to start with and then seem to be out of it anyway.
Irrops: Slight BA win. More flexible and though things aren't ideal I find it's easier to get help when things go wrong.
Cost: EZY win, though often marginal especially if I'm checking a bag. The main difference seems to be that BA's prices go wild at peak times or when booking at short notice, whereas EZY is rarely unreasonable.
FFP: Obvious BA win, though EZY plus is very useful in its own way.

Overall I'll opt for BA if the cost differential isn't too unreasonable but the EZY product is very solid too.