I took a trip to LAX a couple weeks ago. Flew out on United p.s. in BF (BOS-EWR-LAX) and returned on JetBlue Mint (LAX-JFK-BOS).
Mint was superior in every way.
On my EWR-LAX flight on United's p.s. BF cabin, the seats were nice, but weren't long enough (footwell was quite restricted) so I wasn't able to actually lie flat (I'm 6'1). AVOD was limited (not exactly, it's just that there wasn't much that I wanted to watch), and the food was just marginally better than domestic F.
On my LAX-JFK flight on JetBlue Mint, I had one of the suites, and was delighted to have a seat where I could actually lie down. The TV was huge, and I appreciated the fact that it was actually a TV and not AVOD. With a TV, at least the channels broadcast shows on a schedule, so that if I didn't like what was showing, all I'd have to do is wait half an hour and check again. The food was good although I felt like the "taste theme of the day" was bitter (which, if paired with the right beverage, is pretty good). The seat kept punching me in the back (the lumbar support kept alternating between firm and soft, and the I made sure that the massage feature wasn't on), but a pillow between my back and the seat solved that problem. (I've tried wiping down the seat controls with the hot towel to see if it would help, it didn't) I told them about it so that they could fix it and they gave me a $200 voucher for the inconvenience.
The amenity kit felt more like a box of samples, but they seem to have listened to people's complaints about there not being anything useful in it, and have added individually wrapped toothbrushes and travel sized tubes of toothpaste in the lav. They were also "testing" a new product (Gold Bond lotion for aging skin) and had that in the lav as well. Near the end of the flight, they handed out bottles of the lotion to everyone on the plane, including Economy.
I'll definitely fly in Mint again once they start the service to Boston!