I'd take Bryant, Galloway and Glenn in that order.
Depth chart says Galloway, Bryant and Glenn.
In my opinion, Bryant has much more upside than either of the other tow. He also did respectable for a rookie last year.
I'd also take Bryant before the others for the sheer fact that he has the best potential to break the big plays. That will be the only way a Dallas receiver will be able to put up decent numbers this year because there will be no consistency on that offense. (unless consistently bad)
Do yourself a favor and let them swim in the FA pool for a while until one of them shows you something.