There really is no comparing the two. Bill is really old school, almost to a fault, on the other hand I really think draft wise he seems to be building for the long haul. Johnson built a hell of a team, but he did it with Herschell Walker trade picks, got fortunate to have Aikman fall in his lap, and there was no salary cap, and very little free agent movement in his early years. Johnson laid his share of eggs in drafting players as well. The only difference was he had more picks and thus more chances to hit on his picks.
My best guess is with Parcells at the helm next year his style of coaching won't change, but our success rate will continue to climb because he is building a team that fits his style of coaching rather than adapting his coaching style to fit his players. I find it ironic that he probably adapted his coaching style to his talent available his first year, and he was the most successful, record wise, but it probably delayed our rebuilding for a year.
If Jimmy was our coach next year he would probably be successful as well, but would just do it differently. Jimmy did a great job for us, but lets not fall into the trap of thinking he's the cure all, he couldn't get it done in Miami, in part because he was hamstrung with Marino in his later years and that was a puzzle piece that just wasn't as good as he was in his prime.
I guess the short version of the answer to this question is: either one would win next year. We will be better and we will be playing a bit easier schedule as the third place team in our division.