Nobody calls the captains top tiers, not even the blatantly strongest like Shunsui or Ukitake.
Nor were Shikai Aizen, Shikai Yamamoto considered god tiers.
Doesn't matter what people call them. Aizen was really the only character on a tier of his own (and Yammamoto who didn't do shit all), the top tier can't be defined by him at that time. Maybe later once we were introduced to more characters.
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
Tomatoes Tomatoes, we know Ichigo was comfortably Captain lvl back in SS, with his Bankai alone he was food for Grimmjow. We know this because even after gaining the Hollow Mask, he could only match Grimmjow, heck he was on the backfoot most of the fight. Like I said, the #6 Espada literally forced Ichigo to evolve past a Bankai, which was adequate for most Captains at that time.
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
He died, served his purpose in the story. He was never meant to be some final villain of the story I don't see why he has to be relevant after his death.
You're better off comparing Kaidou to Ulquiorra than you are the All Stars/Tobiroppo. He was that big of a threat to the MC during his arc.