I own the F1 and had the AD900 and MA900.
All three are very airy and throw an expansive out-of-head soundstage, AD900 probably had the biggest and most airy, and brightest but in a nonoffensive nature IMO, but the Sonys have the edge in the speaker-like ability to reproduce sound "out of thin air" because of their more open-air frame.
I kept the F1 over the other two simply because of it's very smooth and analog timbre, It's very forgiving (read: warm) but still manges to sound quite natural , espically with the singer-songwriter genere of acoustic performance.
If you're looking for a lively and dynamic sound sig with some sparkle in the highs and some oomph down-low i'd go for the MA900/AD900x.