This might be a biased view because I'm a staff member and long time pilot of one of the SWA's but here you go...
Who's been around longer? I believe thats virtualswa.com
Who has the most pilots? swavirtual.com (through quick roster searches)
Who is the most active? swavirtual.com (taken from the website for current online flights) This one had 16 activly flying, virutalswa.com had two, the rest had zero). Also, according to teamspeak viewers, swavirtual.com had 7 on, the rest of them (that have teamspeaks) had zero on.
I can tell you that two of the airlines you have listed are 'spin offs' from swavirtual.com from former pilots of that airline.
Hope that helps!