By the way, I still think a motivated Messi under a different, competent team can do lots of damage in Europe.
Maybe he's thinking the CR7 way and being selfish about his legacy. I can't blame or condone him for that.
CR tried to up his legacy, but in order to do that, he had to go to a suffering team in Europe, where in case of success he'd be in the limelight as their savior or leader. Messi can do the same, and join a team with no European results and help them achieve that.
Tactically, his best move, if Pep wants him, is to join City. They have a great team that is missing something, and with the addition of Messi and a serious reliable defender, he could win the Champions League with them.
Other than City I see no options for him to really up his legacy. PSG, Bayern, Liverpool are already very successful without him. And he can't lift a weaker side with multiple problems, just like Ronaldo couldn't do it with Juventus.