#1 Roman Reigns
Yes, the most popular narrative right now is that The Shield only exists to get Roman Reigns over. While he gets booed when he is on his own, he is cheered when he's a part of The Shield. As true as that may be, somehow he doesn't feel like the 'fighting champion' he promised he'd be. And this is because of the drama surrounding The Shield.
If The Shield does break up, the Universal Championship will be the focus of the red brand again. Is the title really being defended a lot more times than it was when Lesnar was Champion? Universal Championship matches still seem like a rarity, despite the narrative that WWE tries to sell us.
Roman Reigns always commands a reaction. And ultimately that's what matters, not whether he's getting cheered or booed, really.
In my opinion even Reigns would benefit from a Shield break up!