All three are plentiful and relatively cheap - I don't think the spread between a nice FP and a nice High speed or F14 is really that big. All three were played to death in arcades and may show varying degrees of wear.
They are all great games. I would probably lean toward high speed of the three, but you really can't go wrong. ANd yes, Firepower will require more work/care to "bulletproof" as the System 11 games are much better designed.
Firepower can also play pretty janky if not given a lot of attention. As a baseline, you want to be able to hit that top lock shot with the right flipper.