I saw the Incredibles once, then only saw it again as a double feature with the sequel. I thought the two were really on par with eachother in terms of quality, tbh. Could be some nostalgia because of the time between the between the original releases?
Regarding Incredibles 2 (and largely LEGO Movie 2, to some extent):
The 1st Incredibles came before the big MCU Superhero explosion, and it's a movie that's very personal to me. When my mother could still walk & function relatively normally, we saw it for the 1st time in the theaters during a trip to Disneyland & California Adventure, the 1st time I'd been back there since I was 5. We both loved it, which says a lot because my mom hates action movies. It was clever (the big thing that shut down the superhero world? The legal system!) and explored superheroes like I'd argue no film before it had ever done: through the lens of family.
After almost 15 years of waiting, we finally get Incredibles 2 and...it just felt like the sort of movie Disney would have made in 2006 if they'd rushed out a quick sequel to the 1st film. In the 1st film every character in the Par family had an arc. In the sequel, Mr. Incredible kind of has an arc, and while Elastigirl has her action scenes NO ONE has anything to do in the film. Dash & Violet, especially, are just kind of "there". It feels like half the movie is dedicated to "oh look at that Jack-Jack! He's so wacky!"
The entire 1st film is devoted to building up the family and then bringing them together at the end. The 2nd film keeps them separated, so they can't even play off each other. The family dynamic has actually regressed since the 1st movie, rather than moved forward. The villain is extremely lame, predictable, and has very poor motivation, especially by Pixar standards.
The 1st film just embodies a very special time in my life, and by comparison the 2nd film is just so...empty. It feels as soulless and cash-grabby as the MCU movies that spawned in the original film's wake. It feels like a movie that was made because someone (i.e. Brad Bird) was contractually obligated to do so, not because they wanted to make it. Is it a bad film? No, but despite some funny moments I can't really point to anything in the film as anything remotely special. I only own it out of obligation.