Dragon Ball Super: Jiren Or Vegeta

It's actually an understatement to say that Vegeta loses to Jiren in the Tournament of Power. The Universe 11 warrior has the upper hand throughout the fight and even takes the time to deliver an offhand beatdown to Goku in between attacks. After completely and utterly manhandling the Saiyan prince to the point that bits of his life flash before his eyes, Jiren pulls out the big guns and blasts Vegeta with a Power Impact. When the battered Vegeta retaliates with a powerful Final Flash, Jiren not only takes its full force willingly ... but remains completely unharmed by the attack, and actually takes the time to admire Vegeta's move before knocking the Saiyan out. 

The beatdown is just about as one-sided as they come in the franchise, and as such, should be pretty conclusive proof of Jiren's absolute superiority. However, as stated, forms are a massive game-changer in the "Dragon Ball" universe, and it just so happens that Vegeta has something pretty powerful up his sleeve.