I share randcraw's recommendation of Harper's and The New Yorker, as I've subscribed to both and found their writing quality to be excellent. If you'd like to try them out, I recommend reading some of the past "Easy Chair" columns in Harper's for short-to-medium-length reflective essay articles. In The New Yorker, "A Reporter At Large" features are excellent (as they are thorough and often impactful to shaping current events upon publication), though the writing style is relatively lengthy.
If you like science reporting, The Atlantic has excellent reporters with this focus. The Scientific American and The New Scientist are also worth considering (along with the news and analysis-focused articles in the journals Nature and Science), though I've personally read The Atlantic more often as I'm also interested in the publication's articles about general topics outside of science reporting.
If you're interested in geopolitics, I highly recommend Foreign Affairs. The authors and contributors typically have interesting backgrounds in government or academia, and the essays are in-depth. Similarly to The New Yorker, the release of certain articles is itself newsworthy (often as senior policymakers of various countries are often guest writers)—as a direct result, the publication is closely read by senior policymakers of different countries. I also recommend The Diplomat as a comparable publication, with a specialized focus on news and analysis about geopolitics in East Asia.
If literary writing interests you, I would also recommend looking into some literary journals, such as The Paris Review, The Baffler, The Hedgehog Review, The Malahat Review, and Ploughshares.
These days, I personally listen to the audio versions of The New Yorker's Reporter At Large segments and The Atlantic's science reporting when I can. For the remaining publications, I typically download the ePub or PDF versions for reading on an e-reader (minus the publications that don't offer their issues in their format), and read just the articles that I find interesting on my commute.
For you personally, I would recommend identifying topics of interests that you are passionate about. You can then try to find high-quality publications about these subjects, which may or may not be on this list. If you're more interested in the focuses of the publications you read, you are more likely to develop a habit of reading well-written articles, which is helpful for improving your own ability to write.
This is a great response, thank you for taking the time! My current interests vary more or less around philosophy of mind, metaphysics, technology (less technical and more about our relationship to it), and sociology. I do have some sources for these such Aeon, Nautilus, and a couple of others, but was curious what other people deem as well-written magazines. I'm taking a look at some of the ones you suggested, thank you.
