soloing Suzaku as 75 RDM I guess, first time with NQ af dusk, swift belt, and no dchap yet.
Pretty sure she was the height of RDM solos back then, Seiryu was too luck based for me to say it was the hardest. Sometimes it'd be easy as hell, other times a very quick death. On average I don't recall it being all that difficult.
Suzaku would consistently be a truck, though.
Oh, and getting a Dalmatica, like a year after I joined a HNMls. That felt pretty amazing.