Bleach is VERY different in how characters fight in comparison to DBZ and Naruto. The only fight that might make sense is any character from DBZ dead with a halo. It very rarely comes down to who can hit hardest.
Bleach fights tend to have a science to them, so if Ichigo hypothetically just spent a billion years getting really good as a shinigami, he'd still get his face caved in by Aizen due to the way Aizen fights. Mostly characters have to exploit a glaring weakness in their enemies style (Ichigo properly bonding with his sword to beat Kenpachi). It's only been Ichigo 1up-ing people at their own game until very recently with his fight with Aizen.
Ichigo did not just get stronger than Aizen. Aizen became something other than Shinigamis and Hollows when he used the Hyo-whatever, removed all limits on what he could do with "spirit matter" - to the point people sensitive to ghosts would effin' disintegrate near him (possible to scale when the dude with the hat's leutenant was choking standing near the p*ssed off bald guy). Ichigo STOPPED using those powers, he literally threw them away in exchange for something else entirely (not really explained). Ichigo crushed Aizen because - as Aizen was to the Gotei 13 - he was on a different scale of power.
Sorry to have my first post as a ranting essay, but it kind of annoys me seeing Bleach VS Whatever threads... I don't even like bleach that much any more, but I have to see it through to the end now...