It's hard to gauge how good Aikman actually was, because he had the best of everything around him and he didn't squander it. So he wasn't bad, we can cross that off the list. But name a QB and drop him into that offense - you could list A LOT of names before you start getting to some that wouldn't have succeeded.
You're behind a great OL. You're throwing to a bona-fide #1 WR. You have good 2-3 WRs (Alvin Harper/Kelvin Martin/Kevin Williams). You have a good TE. You're handing the ball off to the all-time leading rusher.
I'm not saying this is the case, but you could argue any QB who wasn't actively horrible could have won at least 1 SB with that offense around him.
The case FOR Aikman, is that he enjoyed all of the successes a guy in his position was set up to achieve. Pro-Bowls, Super Bowls, and the Hall of Fame. He did what he was supposed to do.