Loved this lots, to be honest. Like, flaws and all, it's just such an ecstatically orchestrated fusing of all of these storylines, ramped up to the biggest possible scale while still feeling tangible and exciting with that firm grip on every character (possibly something that could've only been done with both the fleshing out and goodwill of this many movies leading up to it, but if nothing else these movies have always done great job of both nailing the essence of a character and making them their own for the screen).
There are moments that are so joyous that they honestly choked me up (such as []), parts that are so blindsidingly funny that you're not sure how they're working amongst the chaos (unlike sometimes in the MCU where I feel the comedic beats are misjudged or added in for the sake of wanting to relieve the audience of any emotion other than happiness after what it feels is too long), with elements that are so gleefully twisted in their morbidity that I'm just happy they made them work as seamlessly as they did for this type of movie that will be watched by untold millions of children, and just a lotta super fun, unexpected revelations and surprises. And for a movie that's been marketed to death, the fact that from the opening scene to its finale, realizing how much of it was new was its own quiet joy. This kind of feels like an anti-spoiler but, there are even big shots from the trailers that seemed to have been made only for them, and that's weirdly refreshing because it doesn't give you the sort of expectation of mentally building where you expect the plot to go because you've already seen certain things in its advertising. I'll never forget the fact that in The Winter Solider I knew a certain character wasn't dead because a bunch of his big trailer moments had yet to happen. This makes you think something similar, and then pulls the rug out from under you, and I think in the best way.
It's hard to compare it to any of the others in a way, and even to the other Avengers movie. But if I had to inevitably rank, in the former category, knowing how I felt watching it, and still with my gut reaction hours afterwards, I'd put it Top 3 with Black Panther and the first Guardians, which obviously means, despite how much I love Whedon and what he did with his two (particularly in my opinion, the very undervalued Age of Ultron) this is Top 1 amongst the other movies that share the Avengers title, or even Civil War.
I just thought it was blast in pretty much every way something like this should be, as well as perfectly tantalizing and uneasy in its thrills in the way it should be for a movie with a year-away direct continuation.