In popularity, MCU has probably peaked. In overall quality? It's hard to say. Marvel used to have a really high quality control, which sometimes resulted in formulaic stuff, but at least you always knew they wouldn't release anything truly bad. Those days are gone. The MCU has tried to be more director-driven, but somehow that hasn't worked out either. Eternals appears to truly be Chloé Zhao's film, but many people dislike it and it wasn't a hit. MoM and LoT were intended to be very director-driven, but by my understanding that wasn't entirely true for the end result and neither one of those films is universally liked. Something that needs to be done (and has been said before in this thread) is paying more attention to characters that have been recently introduced, instead of constantly introducing new ones. But then again, I'm really excited to see their versions of X-Men and Fantastic Four and that's true for a big portion of the fan base. It's all a bit of a mess.