What is most contested role?

Mid, top, RAD, jungle, support

I'd say mid

Mid for sure, I don't remember a time where there was a more contested role than Mid lane.

It changes depending on when you queue up. There should be an indicator there when you select your roles.

It used to be mid, but the roles have become a lot more even recently.

Support

I'd say Mid hands down any other time, but these days I think Jungle has way more carry value(and a result more people flooding into the role) attached to it.