Canelo >>> Lara. Plus it would be for the middleweight crown assuming Canelo beats Cotto. And not too mention a super fight.
I think Lara is a solid fighter, he is skilled but he is no Mayweather like you say or else Lara would be dominating 154 but he hasn't. He's always in these super close fights that he narrowly wins or narrowly loses. He was in a super close fight Vanes, he was in a super close fight with Angulo for crying out loud who dropped Lara twice and Lara is going to be a big step up for Golovkin, who is bigger, stronger, more experienced, more technically sound and all around better than Angulo in every possible aspect? I don't see it bro. I think guys like Martin Murray and Monroe would beat Lara at middleweight because they are actually middleweights. I guess the only thing I see from what you're saying is Lara has a particular STYLE of fighting that Golovkin hasn't seen recently as a pro, but the size/strength difference and CLASS all favors GGG, heavily. If Lara was bigger, naturally, and stronger I think it would be interesting but he's not. I think Lara is talented enough to hang with some top middleweights, but Golovkin isn't one of them.