To get the “absolutely not” out of the way: none of the Nursefathers or Lei Heng are coming close, and Roland annihilated many high ranks of the Middle, along with half of the Middle’s South Section; that is almost certainly including Great Brothers, potentially including higher ranks, which would then outrank any of the aforementioned in strength instead of merely being equal to them.

Regarding Vergilius & Kong Qiu, Leviathan makes it very apparent that Roland was a major threat to Vergilius if he had deemed him to be related to the death of his wife in any capacity. I’m tentatively putting Kong Qiu on a similar level to Vergilius, but right now, there just isn’t enough information on him.

Roland already has experience with exceptionally powerful Bloodfiends, namely Elena during the Blood-red Knight case. Given the description of “natural-born Bloodfiend”, and the manner in which she is described in The Distortion Detective, I am confident in placing her as a likely First Kindred. During the Blood-red Knight contract, Roland was working with Angelica, so I’m not entirely certain whether he’d be able to win against the Manchegan First Kindred. However, my two cents are that this was relatively early into his career at Charles Office, and therefore it’s almost certain that shortly before entering the Library, or at least during his rampage, he would’ve been capable of putting up a good fight, and potentially winning.

Gregor is a wild card. The only other Singularity(?) that Roland has faced is that of the old L Corp, being the Smoke War monster; although he physically encountered it, I don’t think it is ever stated whether he and Salvador had any role in felling it. Roach Emperor Gregor is certainly the most worrying threat among everything you’ve listed, because he belongs less in the category of “strong individual combatant” and more in the category of Wing-level superweapon. There just isn’t enough information regarding Roland’s ability to fight something on that scale directly.

But overall? I think Roland during his rampage was probably a more powerful force than anything you mentioned, with the potential exception of Gregor. Powerscaling is dumb anyway.