I knew this thread would be unpopular but Keenum is my choice.
However, as noted there are several options and the Cowboys need a solid backup, so they would be only wise to go ahead and bring in solid competition for Dak.
He's never had to compete for his job, and any respectable quarterback would have done well behind the 2016 offensive line with Ezekiel Elliott running the ball.
But since then, Dak has gone 8-8 basically twice- with the Eagles resting their starters and allowing the Cowboys to get to nine wins, and 10-6 once.
In the weakest division in the NFL.
So the Cowboys NEED to bring in competition at quarterback.