Cannot really decide, on one hand, would be nice for Pep to actually win another CL and with Messi he actually has a chance still. Also whoever on board will sign him, will have to agree with giving him more control over our transfer policy, which has been directly board-lead for years. I doubt Valverde or his predecessors had much to say about who we will get and who we can sell, as it has been more marketing project under Barto and you just do not sell your stars. Good examples being Griezmann signing or Malcoms weird transfer and how suddenly Perez and Fati were promoted to first team, after alot of fanbase complained about not including youth in first team.
He is also good with teaching the ways for younger talents, although it really depends on player as much as coach (remember Bojan!).
On other hand, i have a feeling, it may ruin his legacy, just like Mourinhos second stint in Chelsea ended really horribly. He does not have a golden generation he can benefit from, there are not upcoming masses of talents in La Masia and i really did not like how the team played and looked in his last year here as i think he went too overboard with his ideas. I far better enjoyed Luchos gamestyle.
Also Pep ever since Barcelona has managed teams which have been by far richest in the country and his results are pretty meh. Majority of Bayern fans i know, really did not like him that much, as he never could replicate Jupps results or gamestyle. Sure he won Bundesliga, i am pretty sure Valverde is also capable of doing that easily.
In Man City he really only had 1 impressive league season and he has been outplayed by Klopp clearly this year, not to mention his embarrassing defeats in CL.
So just getting him back, because he is Pep, no thanx, but if we are looking for coach and he is available, he may be the best choice at the time for sure.