IMO, the most under-respected Cowboy quarterbacks were Meredith, Morton, and White. Meredith got hammered by opponents when the Cowboys had O line problems, but he was tough and hung in there. Morton played some great games in relief of an injured Don Meredith. Then in '69 when he took over for Meredith, he played one of the toughest Thanksgiving games ever. He played with a separated shoulder but still threw two TD passes in a tie against the 49ers. And White did a great job taking over for Staubach. He really got robbed in the "catch" game, or as I prefer to call it the "snatch."
These were all good quarterbacks. I wouldn't say they were as good as Staubach or Aikman, but they were good.