With that kind of logic there's no reason for any player to join any club that isn't Barca, Real, Bayern or Juventus. We've certainly based a lot of our transfer policy on taking players from non CL clubs and selling them the dream of CL football.
If you assume Alexis has 4 years left at the top, if he wants to win the CL then spending one of those 4 years outside the CL isn't really a good idea, and then spending the 3 after that at Arsenal is probably not too great an idea either.
Of all his potential destinations, City are his best bet of the CL.
It's funny how Guardiola was the biggest change for City last season but this season I don't even think I've heard his name mentioned. And the majority of fans appeared to have given up on Wenger but we're somehow expecting the players to not have done the same.
If I was him, even if you were forgetting the money and who had the best players, I wouldn't want to spend another season at Wenger's Arsenal. Especially after I'd just had the best season of my career and the rest of the team was unable to get anywhere near to my level. Players in that situation leave 5th placed teams to go to 1st / 2nd placed teams all the time and in his 3 years here I think he should have seen enough to suggest a big turning point isn't just around the corner.
If your ambition is to win the CL and PL then I'd take City led by Guardiola over Arsenal led by Wenger any day. We're perfectly capable of making a couple of buys and building a squad capable of competing but I wouldn't trust Wenger to keep the momentum up for 38 games and I wouldn't commit basically the rest of my career to him if there was another possibility available.