S!
I use 120 degrees (with San's FOV changer) for cruise and while searching for targets, switching to "Wide" from time to time to zoom closer. During dogfights I keep the 120, switching to "Wide" to take a deflection/close shot. I sometimes use the strongest zoom (don't remember the name for it) to spray the enemy from far with MGs to make him turn
For normal cruise, I feel the "Wide" is like having tunnel vision. Thus, the need for San's FOV changer.
EDIT: I personally don't understand why are we limited to these limits of 20-~90degrees. Why can't we set anything we want? Sure, it will go distorted if you go too far, but it'll be your own eyesore
.. On my 30" screen, viewed from an arms length (~1m) 120 degrees still looks nice and IMHO gives me a more realistic view of the game world. We do have ~180 degree FOV in real life, don't we?