This is just my pure opinion, but I'm basing it on my best judgement.
Dallas would not hesitate to draft Tyron Smith over:
Nick Fairley
Da'Quan Bowers
Robert Quinn
Prince Amukamara
Nick Fairley is a 43 3 technique. He is a quickness player, not a power player. He is a shade under 6-4 and undersized for the 5 technique or NT position. I think he's a 43 player only, imo. He doesn't use his hands well according to Warren Sapp. Plus, he plays plays high, and doesn't play with the same consistent motor or intensity on tape. Furthermore, he has two years of junior college and one dominant year at Auburn, in two years at Auburn. There are questions about his work ethic, and he didn't lift at the combine or his pro day due to a shoulder injury. Plus, his body didn't look good at the combine and looked better at his pro day. Fairley appears to be a classic boom or bust pick, and Dallas would be wise to stay away from him for that reason alone. I think he would have to play Jay Ratliff's position in the base defense, and he plays too high and isn't a power player. He would be a project at NT unlike Dareus. It should be noted that Fairley isn't scheduled to visit Dallas, and I don't think that is smoke screen, either. However, he's still a top 10 pick to 43 teams and probably will not get past the Titans. The Titans like Jake Locker, but I don't think they would pass on Fairly for Locker. They like Andy Dalton, too.
Robert Quinn has to prove that he can play in a 34 (rush, run, and coverage), and he needs to get stronger, especially against the run. Plus, he has the medical issue and didn't play football last season after being suspended for the season, in an agent scandal. It was a really bad choice that must be in the back or your mind, no matter what. The Cowboys like Anthony Spencer more than some fans, and Spencer's play in coverage and against the run couldn't be matched by Quinn for sure. Spencer has more power, and Quinn would probably need to start off at Ware's position. How is he getting on the field early? Are you going to draft a situational pass rusher at 9? I don't think Dallas will. I think Ware and Spencer block Quinn, and Quinn's best fit early on will probably be in a 43. Quinn has tape where he doesn't play the run very well; plus, he has to show that he can project to outside linebacker in a 34, after looking stiff in positional drills and not testing as well at projected at the combine. Dallas doesn't have the luxury to wait on Quinn or put him on ice. Plus, Dallas has two of its best players on defense in Ware and Spencer. Quinn's pro day will be important.
Bowers is a 43 DE, and that is the way to get the best out of him. Asking him to 2 gap as a 5 technique and kick inside isn't what he is as a player. He is undersized at 6-3, 280. He doesn't fit the scheme. He isn't Bruce Smith. Plus, he has the "one year wonder" tag and the medical issue on his knee. I think there is some bust potential with him. Dallas will not take him, imo. Bowers doesn't have elite burst or quick twitch ability, and he is risky, imo.
Prince Amukamara isn't a top 10 pick, imo. He's a good CB and a high character guy. However, I think people who really do their homework know that Dallas will not take him at 9.
The Cowboys would not hesitate to take Tyron Smith over all of these players, imso.
When you add the offensive players, Smith trumps this list, imo.
Fairley
Quinn
Bowers
Amukamara
Green
Jones
Gabbert
Newton
I think Dallas wouldn't hesitate to draft Tyron Smith over these guys, too:
Cameron Jordan
J.J. Watt
Gabe Carimi
Nate Solder
Derek Sherrod
That leaves three players:
Patrick Peterson
Marcell Dareus
Tyron Smith
Dallas would be wise to anchor at 9, and take Smith, a blue chip, cornerstone player in their offensive line for the next 12 years.