Q: or F# instead of Gb etc?
A: F# and Gb are equivalent choices because they each have 6 degrees in the key signature, but it may be more often called F# for two reasons. one is kind of like the C#/Db case where F# is more verbally clear in a crowded room, but also it is more common for keys to borrow flatter notes than sharper ones. which creates no problems at all in F# where as in Gb it immediately creates double flats. actually i can think of a 3rd reason. F# as a note would be much more common than Gb because F# is the first note to go, in sharp keys. where as in flat keys Gb is is the 5th note to go. so people are already more accustomed to verbally hearing the words "F#" than Gb