Not voting as I assume I can't vote for all, and they all appeal in varying amounts.
Now, I'll suggest a few questions as to what YOU'RE seeking in a game.
How do you feel about hex-based? Sky Galleons is, and Aeronef with movement units and all sixty degree turns is as good as, though I've played both without a hex map.
Do you follow 'VSF aerial games are predreadnoughts in the sky' dictum? Castles in the Sky and the scarce but occasionally available Leviathans(hexed) are both more towards the Edwardian timescale of BIG ships.
I think Imperial Skies is somewhere more in between. Robin will probably want to kill me for suggesting such, but I really do think IS owes much to 'nef and add-ons put together by David Manley and others, but the movement system is VERY different'.
Lastly, even the 'out of print' stuff is mostly available for download on Wargame Vault and the like. Few others I've only seeen there, but not sure I'd recommend any.
Personally, I rather like Aeronef, though I think its organization is 'challenging', which has meant my fiddling with the rules, first reorganizing , then fiddling with my own additions makes me rather biased.
Doug