Noah for the simple fact that his position is harder to fill and his skill set is easier to fit pieces around.
I agree his position is the hardest to fill, but how can the guy who's completely inept at scoring from any distance be easier to fit pieces around? Both teams would have a great rebounder, both teams would need shooters around them, and both teams would need a big that can score. The most significant difference between the two teams is that Rondo's starts out with a HUGE advantage offensively, no matter who you put around him.
Because as a C who can cover his man and collapse the paint simultaneously, Noah makes much more of a defensive impact than Rondo, who can really only stop the ball at the top and clog passing lanes if only he didn't then roam and end up playing matador D and swiping with his hands more than moving his feet.
Also, neither Noah or Rondo can shoot, but Noah is going to be 8 feet from the hoop unless he's dropping 6 assists a game from the high post running the whole offense like half of last season for a playoff team. So Noah can score on putbacks, grab offensive boards while still keeping in ideal position and not jeopardizing running back on D, and he only has to shoot from 8 feet out. Rondo can't shoot, but he has to be at the 3 point line. He has many skills to account for this, but Noah and Rondo not being able to shoot similarly do not have similar effects on a team.
For these reasons, filling the team is easier. 3 + D guys are the fastest growing commodities in the league now (look at what we signed James Posey for in '07, then look what Jimmy Butler admitted a better and younger but similarly skilled player, gets this year), you need those with Rondo because you gave up Noah the rim protector. With Noah, you can spend 40% of that cost on a great shooter who's just a decent help defender (Korver an alpha dog example of this) and then you have cap $ for a legit max player to pair because of how Noah's skills allow you to save money at other positions for a big splurge, and because you already found your C.