Think Romeu has shown he is as good as both of them to be honest. Besides he plays a different style to both, and it's something we need vs chelsea
He had only one very good match, which was against 10 men Norwich, and other matches he was decent, nothing special. Davis and JWP are more mobile than Romeu, and you need mobility more than power against nimble Chelsea forward like Oscar, Willian and Hazard. I think Wanyama-Davis-JWP combo would be a better fit. They aren't that bad defensively, really, maybe in the start of the season, but lately they've tightened up considerably.
I don't think that the reason why we lost to United. It's more down to a dodgy backpass and an offside goal. When we had Davis, JWP and Wanyama on the pitch, we were outplaying them.