If you fly BA, I highly recommend upgrading to economy plus.
I recently flew to the states and back with BA. Went out economy, came back economy plus. My understanding was additional cost was minimal.
Benefits however were great for a long haul flight. Economy plus got business class food. Which was a 'three course' meal, but the food was great. Detachable remotes on the touch screen displays (which economy has, but doesn't have the detaching remotes). They also had larger leg space, by a decent amount, and the chairs had raising foot rests and greater space leaning back. I'd certainly upgrade to economy plus on any long haul flight now I think (although would probably do it on avios if I'm honest)
Regarding economy however:
Both were good, economy was actually manageable. It was a ten hour flight (slightly longer than New York) and I just watched four films. The film choice was truly fantastic. Django, jack the giant slayer, jack reacher, les mis, robot and frank, the hobbit are just a small selection of the films I could choose from when I flew out probably close to a month ago now.
The only issue I have with BA is the plugs, but that doesn't bother me as the in flight entertainment is so good it doesn't matter.
Think they're also refurbished all their old planes for long haul already (the 747 we flew out on was refurbed), but the 737 I flew to Spain on wasn't.
Pretty sure BA have also just added a bunch of the new airbus and boeings to their fleet as well if my fb feed is to be believed.
As a small extra positive for BA, flying BA from heathrow pretty much guarantees T5, which I found to be a top notch terminal.
kd