I just flew both in and out of FCO (USAirways) and TXL (AB). I'm only 5'6 and I thought the length of both seats was perfect. However, the width of AB seat was definitely worse. I also flew the short a FCO-TXL hop in AB in Y (no business class on that route) and I've never felt more cramped. Pitch is the worst I've had.

I was impressed with AB service aboard (if you need to deal with them on the phone, they are AWFUL) and liked the food ex-TXL better than USAirways food ex-CLT.

Both are oneworld partners, so you get access to the same lounges.