It's Rodri. He won't be the most popular choice because the things people notice the most are goals, assists and dribbles.
To be able to complete the most passes in the oppo's half under pressure while also stopping many attacks and contributing decisive goals and assists is something I appreciate higher than extraordinary skills in assisting, scoring or dribbling (unless you do all three things like Cruyff or Messi).
David, KDB, Haaland... are geniuses in one or another department. Rodri is exceptional in that he's good in literally everything, from defending at a very high level to completing the most passes in Europe to creating chances and scoring vital goals.
So, David, Kun, Kevin, Erling, Phil, Yaya... are extraordinary in one or another department, but in terms of the whole package of skills Rodri would be more important than any of them in a Pep team.
In an anti-Pep team, one that doesn't value possession, patience, intelligence, etc., the other City legends would be arguably more useful. But in a Pep team it's Rodri. He's phenomenally complete and fundamental.