Probably Eubank jr... I think Golovkin is going to box Brook for a while to make it last a little longer.
Eubank Jr purely due to size. As above, if they boxed Brook and GGG could be even for a while but as soon as GGG has had enough of playing around he will walk through those Welterweight punches.
Eubank all day long, he is quicker, more unorthodox and has a better chin. He's also mentally stronger than Brook going into a fight like this. He is deluded but will genuinely believe he will win, unlike Brook who is after the payday. And he's a middleweight, which helps.
That's actually a bit of a poser... despite really not approving of the Brook fight I've got to say I'm probably more intrigued by it than by the Eubank fight. Stylistically I think Eubank plays right to GGGs strengths... it could be he'll make it tough for GGG with his strength and speed, and likely he'll last longer than Kell, but Kell brings speed and adaptability, personally I rate him as a considererably better boxer than Jr. I don't think Golovkins gonna be beaten at 160 with size or athleticism anyway so Kell might be best served by keeping his weight fairly low to maintain his speed and stamina - at the very least it might give us some insight into how Golovkin could be beaten - or at least troubled.
This is what I was thinking. Knee-jerk reaction definitely falls to CEJ matchup but upon further an@lysis the two matchups might be closer than one might think.