Best option for SFO-TXL
 

Looking to book a trip from SFO-TXL and curious what would be my best airline options, being WP, that would open up preferred seating?

From what I can see, BA isn't offering this, does Air Berlin?

AA does, but looks to codeshare with Air Berlin from either ORD or JFK.

Probably not a great deal of options.

Since you wrote about preferred seating I assume that you are looking for Economy class, right?

I would prefer SFO-LHR-TXL on BA over a red-eye transcon with a connection in ORD or JFK.
The SFO flight is quite nice on the A380 but currently B747s are used on both BA284 and BA286.
Rather than spending money on advance seat selection you could try to score an upgrade to BA World Traveler Plus (Premium Economy) while booking.

[mod hat] Since this is about comparing different OW airlines I will move this to the appropriate forum [/mod hat]

I'd try SFO-ORD on AA then ORD-TXL on AirBerlin