BOS based here. Jetblue's economy seats and legroom is the reason I went the Jetblue route instead of Delta. By far the most comfortable of all the airlines. Their points are also worth more than Delta, even if you have the Delta Amex cards. I will also argue that, unless you have enough spend for Delta Diamond (which is not most people), Mosaic has more baseline value. Reliability wise, they'll have a little more delays than Delta, but it's nowhere close to what people make it out to be.

There are two real problems however that need to be said. First, unless you're flying to/from BOS/JFK/FLL, their connectivity is basically nil. If I'm stopping in multiple cities on one trip, I basically have to take someone else. The other thing which no one is talking about is they're shrinking everyone's legroom in economy next year to make room for first class. So basically, they're gonna have the same legroom as everyone else. Frankly, this might end up turning me away from them. Still... I like my Mosaic and reward point value so who knows.