I liked him until birdcage.... Kata is the best post TS villain for sure
Doflamingo is just on an entire different level as a character
At first he gets introduced getting rid of one of his lackeys in the grandline (Bellamy)
Then we learn he controls the slave trade in Sabaody
In Marineford he’s this insane bird man who pokes his head in other people’s business
Then comes PH, where we learn that the leader of the autonomous navy branch manning 6 battleships and controlling everything at the beginning of the new world, is none other than Vergo, Doflamingo’s soul mate and sworn brother
He also controls a mad scientist who once belonged to the navy, supplying him with all kinds of weapons and devil fruits
He’s then established as the kingpin of the underworld, with connections to countless countries and yonko Kaido
He also sold weapons to the government
Later we go on about with Doffy being a CD, his story with Law, his demeanor and ruthlessness overall in controlling Dressrosa
Overall Doflamingo is everywhere in the OP verse, his network and reach especially for a guy who isn’t a top tier in strength show just how shrewd and devious he is.