Think Golovkin is slightly overrated and Brook is definitely underrated.
Also why is golovkin ducking Canelo and kovalev? Maybe because he and his team know he's not as good as he's made out to be.
Said this a few weeks back when Eubank was proposed for GGG. Golovkin has barely fought anyone of note yet. Lemieux and Murray basically.
Kell Brook is a massive step up in terms of in ring quality and I agree with you - I think Brook goes in as slight favourite. Either GGG proves he's the real deal (which is very possible), or he's going to be relying on that weight difference to get through.