Are you really going to sit here and try to posit the notion that every QB who has won a Super Bowl is "by definition" better than every QB who hasn't? I will allow you to retract this statement on your own..
I'd like to see you try, because by definition those other QBs are better than Dak because they have SB trophies while Dak can't even get a game away from the SB.
I know you are going to try to point out regular season stats, but that fails. Lots of QBs inferior to Aikman routinely put up better regular season stats, but none of them could play like he could in the playoffs.
Since you brought up Aikman I went and looked at his last 4 playoff games..
His passer rating in those games were 67.9, 37.4, 37.0, and 70.7. He totaled 2 TDs and 8 INTs in those four games. While I agree Troy had a couple of wonderful playoff runs, after Emmitt and the o-line started getting old he started to look decidedly more mortal himself.
Meanwhile Dak's last 4 playoff games his ratings have been 69.3, 143.3, 63.6 and 89.8. He has totaled 9 TDs and 5 INTs in those games. In both cases the team record was 1-3 in those games.. By any objective measure, however, I think it is fair to conclude that as bad as we THINK Dak has played in these games, he has done more to help his team win them than Troy did for his team. The offense averaged less than 12 ppg in his last three starts, all double digit losses. But you obviously can't ignore Troy's first 5 trips to the playoffs where he was amazing. Those runs are what keeps him above Dak in the minds of just about everyone. But he did have a top 3 rushing attack and a top 3 defense for the good part of his run. When those two items went away, so did he. Maybe just a coincidence though.