#1 AJ Styles
The biggest star in WWE right now is AJ Styles, and that is not even a surprise as everything WWE does these days revolves around The Phenomenal One, after John Cena, Brock Lesnar and The Undertaker are part-timing stars these days.
Styles has taken the mantle of being the top star in the company, and the one thing that proves he is the top guy in the company is the fact that he doesn't need a title to be relevant.
Styles has been on SmackDown Live for over two years now, and he will definitely go down as one of the greatest stars in the history of the Blue Brand, but it is time for a change, and while moving to RAW isn't a huge change as it is like basically moving to your neighbour's house.
However, this is different as Styles is a star that is synonymous with Smackdown Live, so him moving to Raw will improve the show and it will freshen up Styles' career.