Originally Posted by Mwenenzi

Mi Chal Welcome to FT

You have Star Alliance & Skyteam covered so you a need OneWorld ffp

BA is good for short haul awards, but has surcharges. You can move avios from BA/IB/avios.com, so IB is also an option.

AA is good for long haul awards and has no surcharges, except on BA flights.

All need 4 flights in the home airline ffp to get status. That is you need 4 AA flights to get AA status or 4 BA flights to get BA status. No idea about IB flights needed for status. High status get you free lounge access.

BA expiry (36 months no activity) is better than AA (18 months no activity). But if you fly eligible IB flights credited to AA or BA expiry will not happen.

There are some BA vs AA threads linked in post 2
If you will never fly AA go for BA.