AGES does not emulate System 16. System 16 is arcade hardware.
Woo: The best would have to be MAME, but frankly, MAME's current s16 driver blows. It's currently being rewritten by an acquaintence of mine though, albeit slowly..
No, I don't know when it will be done, nor does he, or anyone associated with him.. Any large progress he makes would be posted on MAME's WIP page..
You fail to mention that none of those listed are more advanced than MAME's broken system16 driver (especially System 16 Emu, it's long been dead). And Final Burn really just goes after After Burner and Galaxy Force hardware.
And if you want to list everything, there's also Calice, and that Cygwin compile of Final Burn (it has limited S16 support, including the poor AB and GF support FB already has.)
I'm not quite sure what inspired me now.. Something, someone else mentioned in a thread... thinking back it was to do with SEGA Saturn and that AGES pack that I got with it (afterburner, space harrier and outrun)
Anyways, a lot of people here though not "experts" on Sega System 16 emus are just like me, emuholics of many other systems out there and I did get what I was looking for... Perhaps not entirely appropriate, but the crowd here are "in the know" ;-)
I guess Samor meant the popularity of the actually systems during their productive (profitable) days.
Or maybe the current interests from the gamers.
Either way, the dev's interests are obviously related to the challenge and therefore satisfaction of emulating certain systems, and that doesn't always reflect the "popularity".
You might think that the dev's interests are usually more of a factor that decides whether a system is emulated.
But as the number of dev's increases, perhaps the difficulty (or lack of which) of emulating the system now ultimately decides which systems get emulated.