Kell Brook won't back down from any challenges, like you said, he took his chances against GGG.
Gennadiy Golovkin is a heavy puncher than Terence Crawford, Kell brook can take Terence Crawford's punches here, and this will be an exciting fight.
Comparing Terence Crawford and Gennadiy Golovkin, Gennadiy Golovkin has a higher KO percentage with more experience as well, the fight has 35 KOs of his 40 fights, that was just crazy.
https://boxrec.com/en/proboxer/356831