Originally Posted by DarkSideMoon

That depends entirely on your risk tolerance and goals. You want safe and slow? Skywest/Republic/AA wholly owneds/Endeavor are likely either too big or too secure to fail. Some upgrade quicker than others.

You want quick upgrades to get out of the regionals or to make a lot of money and build time quickly? Expressjet, Whiskey, Mesa, Commutair.

There's no one right or wrong answer, it all depends on your personal situations.