thats not even a question. Crocodile and Doflamingo were really good villains, despite Doffy being somewhat of a Crocodile ripoff.
kaido and BM only have their big names/reputation as Yonko that makes them appear 'strong' but character wise they are rather boring and uninteresting. Kaido is a bunch on incoherent villain traits and BM is a mess/meme.