Fantasia is definitely one of the biggest pinnacles in animated film. Although...it's not perfect. I'd reduce a segment or two, and cut one out entirely. Then it would be pretty flawless. But the animation and music is so often so transporting, I just love it. I also love how ambitious it is, and how Walt tried so hard to get it made only for it to kinda flop a little bit when it came out. The history of it is worth reading into.
Live action Dumbo is, well, like the other live action Disney films...kind of dumb. Again, there are things I like in it, but there's also a lot of things I think are terrible. It updates the icky positive feeling the original gives off in terms of circuses, but it doesn't gel with the period it is set in. The layout of Dreamland is kinda cool, but also a little too...steampunk-y maybe. The emotion of Dumbo as a character, especially in regards to his relationship with his mom still works in this version though.
Last night we watched Peter Pan...and yikes. Out of all these early Disney films, this is the one that has the biggest problematic outdated cultural depictions. It's...really bad. Worse than you might remember honestly. Now, I love the story and the themes, and the imagery...but that one section I am referring to kinda ruins the whole thing.