Interestingly last week had the opportunity to compare BA and eastJet on a LHR -TLS (BA) TLS-LGW (EZY) trip.
BA had far longer and a more protracted check in process and boarding was not so good as I have no One World affiliation so I had to wait until just about everyone else had boarded. Nothing between them in terms of comfort, both aircraft looked somewhat tired. Service quite similar.
Didn't use BOB on BA as no acceptable credit cards but had a pretty acceptable Bacon Baguette with coffee (and a free KitKat thrown in) on the easyJet return as they accept cash.
The only significant difference was the price. Both flights were booked on the same day about 5 weeks ago and there was a very, very significant difference. There is now no difference between them in terms of product.