The Five Best Offensive Lines 1. Dallas Cowboys. Cowboys bashers can scoff if they like, but the team has a tremendous line. It all starts with Tyron Smith, one of the best offensive linemen in the NFL right now. Smith allowed just three sacks last year and is the best run-blocking left tackle in the league. Right tackle Doug Free is a solid run blocker who rarely makes mistakes in pass protection and has not missed a start in four years. Smith is outstanding and Free is good, but the prospects are what bring this line to the next level.