Let's pretend Sunday was his last match and you have his body of work up until then to judge. Where does he fall on your all time list. Top 5? 10? 100?
What we using as a guideline? Because as its an all time list you will have variant of different criteria's.
Like list of best draws, but then how far do we go back?
Work wise how good was he?
What was his best run as a performer?
Overall impact, how many people has he put on, gotten over, what is his legacy?
The problem with all-time lists (this is in general no particular industry) people will often pick their own personal favourites to fill out a list then to think logically about it factoring in people's career , body of work and overall impact.
You got to remember alot of people aren't fans of Cena and because of that they will rate accordingly to their dislikes of him then to do it as a impartial rating.