I'll probably cop a load of flack for this selection, but eh, I'm a complete and utter retard when it comes to my preferences in anime (no accounting for taste, as they say):
Hourou Musuko - accusations of wokeness will probably fly with this, but I don't think any other manga even tries to approach pre-adolescent gender dysphoria with anything like a similar level of maturity, it's problem being that it's a bit too mature for its own good
Infinite RYVIUS - think Lord of the Flies in space, haven't seen it in a while, but as I remember, it handled the source material pretty well
The Sky Crawlers - another Mamoru Oshii film, the story itself is pretty damned depressing (but it starts out with one of the best animated dogfights put on screen) and at the time (might still be relevant if I kept up with more anime releases) was considered an allegory for stagnation in the anime industry/fanbase
Fuujin Monogatari - I haven't watched this in a long time, but I recall enjoying its quaint and endearing feel, included because it's art style is very unconventional
planetES - one of the most grounded hard-science sci-fi titles ever made IMO and considers one of those really mundane things that no-one even wants to think about, that few other sci-fi concepts do, as its premise and makes it work: trash collection in space
Moyashimon - I'm putting this here just for fun, but it's unique for anthropomorphising micro-organisms and making it educational without resorting to fan service when doing so (there's fan service provided by a couple characters, don't get me wrong, but that doesn't get in the way of Microbe Theatre or the series' soapbox nature towards food science)
Related to the above is Gin no Saji (which is a good showcase for the shit family owned farms go through just to survive, or not survive as the case may be, as well as a soapbox for food science of a different variety) and Mari & Gali (a very slapstick series whose intent I really don't know except to bring maths and physics to students). Whether you consider scientific merit in an entertainment medium to be of artistic merit is your choice, though, I suppose.