I'm still enjoying the novelty of trying other airlines, although, having flown almost exclusively with BA and AA for the best part of a decade, I've also found it a little unsettling getting used to different processes and procedures.
I just completed a transatlantic trip with Aer Lingus. Onboard service was perfectly good, seeming a lot more relaxed than BA's, and the food was excellent. I'd be happy to fly with them again.
I positioned to/from Dublin with BA (reward flight). Boarding was messy, with both flights being almost 100% full and the gate agents having allowed passengers to board with too many bags. I was disturbed from my reading by having a bottle of water shoved between my face and my book, like something Pam Ann might do. I really don't know why BA can't get this little stuff right.