Allow me a highly controversial take. Dragon Ball Z.
Now, I do have to try and keep in mind the context of when it came out - I'm far too young to have seen it on first release, so one might say I was spoiled and seen others having built upon it by the time I watched it myself, versus others. But hoooooly cow, I did not like it, at all.
And it should be so cool! Larger than life characters, massive battles, interplanetary storylines, giant lasers... sounds awesome, right? But everything was just done so shoddily. I watched all of the original Dragon Ball and enjoyed it, but was eagerly anticipating getting to Z throughout - only to be sorely disappointed.
There was no real "mechanical power growth" or notion of getting stronger through an organic means. Everyone just kinda magically powered up at just the right time for whatever was happening, but sure took their sweet time doing so. Fights were agonizingly slow, and there was no difference between an attack that did nothing and an attack that won the fight. If you were to show an arbitrary clip of Goku shooting a Kamehameha and causing an explosion/dust cloud, you'd be hard pressed to say whether the enemy shrugged it off or died, because both were precisely the same, as though with each attack Toriyama flipped two dice and if it came up both 6s the fight ended and otherwise the opponent was completely unharmed. You could easily shuffle around the scenes of the Frieza fight and nobody would notice.
I expected long, drawn-out endurance battles where the characters got increasingly tired and beaten down, but kept fighting and fighting over a long period of time until the last blow was struck, but frankly that's not really what happened. Near the end of Frieza's battle, I had frankly stopped even paying attention during an episode, because I already knew what would happen: Goku would throw a punch or two, Frieza would laugh, episode ends. It was SO. BORING.
In the end I gave up during the Garlic Jr. arc, and feel absolutely no desire to go back and finish it. It's a shame, because like I said it should have been so much better than that. I have no doubt I'll get some pushback for this from people who saw it growing up, most likely along the lines of how it was the first of its kind in Western countries and other things doing it better since doesn't discredit DBZ's accomplishments. I can understand and appreciate that, and respect DBZ for its historical and cultural importance, but I have no compunctions whatsoever in saying it has aged very, very badly.