Maybe a boring answer, but I really like the big national museums like the Smithsonian, the British Museum, the Scottish National Museum, etc. There’s definitely something magical about being in a place where you could (and I have) spend days back-to-back and still not manage to see all the exhibits. There’s also something amazing about the sheer variety, where you can see Greek pottery, or Assyrian sculptures, or marine mammal skeletons, or trilobite fossils, or amethyst geodes. The museums are also free to enter, which is nice even if it means you have to deal with crowds at times. Of course there’s also a lot of problematic stuff with these institutions, to put it mildly.
As a kid, I used to love science museums, but as an adult I tend to be a bit disappointed when I visit them. Part of that is probably because they tend to be targeted towards children. But it also always feels like half the interactive exhibits are aging, broken, or just not as cool as you want them to be. Crappy apps running on tablets with cracked screens, broken levers and buttons, audio and video exhibits on shitty projectors.
On the other hand, I’m extremely into natural history museums. I’m happy to spend all day looking at bones, bugs, fossils, rocks, etc.
The Harvard Museum of Natural History has a really amazing collection of glass plant models. They’re interesting not just because of the huge variety of plant species, but also because of the level of craft and artistry that goes into each model.