The top tiers as in the Captains. Aizen was not a top tier at that time, he was a god tier in that verse.
Ichigo was already matching the likes of Byakuya in the SS arc and proceeded to get bodied by Grimmjow, he literally forced Ichigo to evolve past a bankai, and with the hollow mask + bankai only ended up matching Grimmjow, who on paper was the #6. Ulquiorra absolutely body bagged an even stronger version of Ichigo...
All stars and especially Tobi Roppo were an afterthought by the time Wano rolled around.
Nobody calls the captains top tiers, not even the blatantly strongest like Shunsui or Ukitake.
Nor were Shikai Aizen, Shikai Yamamoto considered god tiers.
Grimmjow beat up an Ichigo who couldn’t control his powers very well and got scarred and humiliated to the point of becoming a tsundere for Ichigo once he had a semblance of control. He was the Renji of the arc and that’s it, returning for a cameo later
Ulquiorra was the authors pet, well established as much and the Byakuya figure. He did a good job as a central focus for Ichigo but again is forgotten equally as much as the Tobi Rōppo after the arc. The only people who remember him are Ichigo fans who liked the fight or Ulquiorra Stan’s who like his sad backstory