I am Airberlin Platinum (=Oneworld Emerald) and like AB way better than Lufthansa. I also regularly fly AA codeshares (but the other way around: AA flights marketed as AB).
All OW benefits apply on AB and are usually well honored (except on some fully chartered flights). Fast lanes on both checkin and security exist in most locations. Baggage allowances also work fine.
On the minus side:
- Boarding passes between AB and AA are always a problem because they use different booking systems which are not well interconnedted. Usually reserving a seat (including status benefits for seating) works at booking time, but changing it later is difficult. Online checkin is 30 hours if you can get hold of the Amadeus booking code.
- Irrops handling in TXL is not good. Don't know about other airports
- Generally TXL is not a great airport for changing flights. This applies to everything from security to boarding (priority lines do not fit at the gates) to baggage.
But in terms of in-air service I like AB way better than LH, in both domestic/European Y and intercont J (AB does not have F, and J only on intercontinental flights). I also like the new J seating on AB a lot (it's the same as Etihad's)
Regards,
Stepfel