I've taken this trip a few times with Aer Lingus and haven't had great experiences to be honest. In my opinion the service was very poor and it seemed as if I was almost offending the cabin crew when I pressed the call button for another drink or a snack. As for the IFE, I thought it was quite poor with a real lack of choice. On two occasions my TV was not working for the entire flight. I found the legroom to be quite good though.
On my last 2 trips to NY and LA I flew with BA and must admit, I was delighted with the service. The cabin crew were very friendly, helpful and on several occasions asked whether I needed anything. The connection through heathrow is always a bit of hassle, but I personally feel it is worth it.
I suppose it depends on your own requirements. I always like to relax on longer flights, watch some movies and have a couple of wines - so with this in mind I prefer BA. However, If you're the type of person who sleeps for most of the flight, then it's probably worth going with Lingus as it's direct.
my 2 cent
