For pleasantness and YA high fantasy vibe Le Guin's Earthsea Cycle is great.
For wizard school with a much more mature tone R.F. Kuang's Babel is a great read. Warning though it is much darker and heavier, so prepare yourself emotionally haha.
EDIT: was recommended that I give a heavier content warning to Babel which is fair. While it is thrown around as an HP alternative it is emotionally harrowing, has some extremely violent and disturbing sections, and is generally focused on depicting the horrors of colonialism. A good read, but prepare yourself going in and don’t expect it to be quaint or pleasant.
Earthsea is often described as being rather mature despite being YA. I agree. There's a clarity and immediacy to Le Guin's writing style that cuts straight to the point while also providing clear images and characters which is combined with deep and arguably universal themes and sometimes nice allegory.
Additional to this, the series goes or progresses in surprising directions. As is so often the case, Le Guin didn't intend to write as many books as she did, but used the opportunity to do interesting or personal things with each book. While there's a continuity throughout the whole series, it's not a simple or single story but rather multiple stories with large or important intersections. You could for instance stop any time you like and not really miss out on any satisfying climactic ending.
For Kuang I agree that they are generally enjoyable reads (or rather, exciting or suspenseful, I suppose) but I would strongly hesitate to put them into a recommendation looking for quaint and pleasant.
Her books go fairly detailed into gore and excesses of violence and sexual abuse, more so for her earlier works. So - good reads but come prepared.
Yes I think Babel is a little lighter on gorey excess than the Poppy Wars (which I haven’t read but my partner has described in detail to me). Which is to be expected for books designed to depict the horrors of colonialism.
But mainly mentioning it with a content warning since it’s often tossed around as an HP replacement. I think the first half of Babel captures a similar “wonders of magic school” vibe, although with a lot more caveats about how inequitable the entire system is. It does get extremely harrowing by the end so maybe should include a clearer warning in my post.
And I also think you hit the nail on the head with both the way it introduces the 'magical' world and then pulls the rug out underneath you and protagonist in quite a distressing fashion. Pretty clever actually!