The PL title will always be the biggest trophy. And the biggest achievement. Yes, the football media, European Royalty FC, and United will always big up the CL, especially as City haven't won it.
But let's but honest and frank about the CL.
It's a rigged, setup, staged, managed for TV, group, knockout trophy. Teams can finish 4th in their domestic league and still get into the CL. Teams can finish 6th in their domestic league, get into the Europa League, win the Europa League, go straight in the CL pot 1(Lol!), and win the CL.(Lol!!)
When Liverpool won their last CL they finished 4th in the PL the season before. On the way to the final they lost 3 games and drew 2 games. Barcelona threw away a 3 goal lead in the 2nd leg at Anfield. And Spurs never turned up in the CL final.
Contrast that to when City won their last 14 games on the run to pip Liverpool to the PL title. What an achievement.
Yes, teams are miles better in the CL, but there are no 2nd chances in the Carabao Cup or FA Cup. Lose and you're out. Just like the old European Cup.
What's more difficult? To win the CL or to win the English domestic quadruple in 1 season? Only Pep has ever done that in England. Klopp hasn't. Fergie hasn't. Jose hasn't. Wenger hasn't, Busby hasn't. Fagin hasn't, Paisley hasn't. Shankly hasn't. Let that sink in. Yet you never hear that being talked about in the football media. All you hear from the football media, Liverpool fans, and United fans, is City have never won the devalued European Cup, now known as the CL, which is about to expand with more teams finishing further down their domestic leagues being allowed to enter into it by the UEFA Mafia.
Winning the PL title will always be bigger than winning the CL in my opinion.