I would like to have Olly, Dannii, Simon and Paloma Faith. The panel needs someone relevant, not two washed up ex girl group members with very limited vocal abilities and a band manager from the 90s who can't mentor to save his life. Paloma and Olly are both relevant and would increase viewers to the program, both of them also know the current music charts, Simon can cover the producer side of things and Dannii would be brilliant as she knows how to mentor and judge, she also knows how harsh the music industry is and whats it like to be on XF.
I doubt Cheryl will be back next year now her solo career is back on track, Louis is practically part of the furniture and I would imagine Mel would stay depending on her other judging roles/living in the USA. X factor just hasn't recovered from it Golden Era (2008-2010).