I'll take MUI Goku over Gogeta.
Gogeta smacked down Broly, and MUI Goku smacked down Jiren. Powered up Jiren seemed more impressive than Broly however, which is why I'm leaning Goku here.
MUI Goku was able to take down a massive powerhouse like Jiren in two minutes. It ran out just as he was about to end it. I don't think he's going to have TOO much trouble with Gogeta.
Goku
Kefla
Vegeta