1. Staubach
2. Emmitt
3. Witten
I have to choose guys who I actually saw play and who exemplified the winning/never-say-die spirit of the Cowboys.
I didn't see Lilly play (or don't remember his play) so I'm not going to include him.
Staubach embodies the Cowboys and always will - at least in my life time.
Emmitt is the reason for the Cowboys three Super Bowl trophies and, of course, he's the league's rushing champion.
Witten is just total class. And if there's one guy of this decade who represents the Cowboys, it's him. Yes, even over Romo.