I asked my wife and she responded FFM.
Why? "MMF - Been there, done that, got the tee shirt."
She says that pleasing two horny men is a lot of work! (and a lot of cock sucking!

) We haven't had too many FFM's (more MFMF) so she feels there's still "more to learn" from just having another woman for us to fool around with.
This is news to me so thanks for bringing it up!

I guess I'll be the one doing a lot more work in the future

, though I still love to see her with another man.