Oh, great question. I've never actually compiled a list of my favorites before.
Tessa Schlesinger
https://tessaschlesinger.medium.com/
She has definitely made me a better writer. She's been writing online proffesionally since the 90s. She recently published a list of all her articles about writing that is daunting, impressive, and humbling.
I highly suggest checking that out. I don't read anyone else who writes about writing anymore. Just reading her stuff makes you better thought. PLUS, she is one of the most active and engaging writers on here. I left responses on a few of her articles and was thrilled when she made the time to read some of mine. She highlighted and commented about things she loved and things she adamently disagreed with (A lot! Lol) Which led to very constructive conversations with her that have improved every aspect of my stories on Medium. I try to lean into critisism. I endulge in it just as much as praise.
Jason (Editor for Fuck Niches)
https://presley-jason.medium.com/
I don't know if reading Jason improves my writing, but he encourages my spirit and lightens my mood. Plus, I write for his publication now. I suggest every writer does the same.
https://medium.com/fuck-niches/5-big-reasons-i-wont-ever-pick-a-f-king-niche-ever-af7dcff0bbf7
James Cussen
https://medium.com/@jamesgcussen
I've been extremely grateful and humbled by the amount of writers that have followed me who have way more followers than me and are much better writers than me. James is one of these writers. I always check out new followers right away, and I couldn't stop reading James. He is a stunning author. My go-to for philosophical teachings, life lessons, and historical stories about ancient Greece.
The great thing about Medium is there are so many great authors on here. At first I thought there was a small percentage of truly great authors, and then there was the rest of us. But I'm starting to find out, everyone has a lot to say, and is actually quite good at it. Instead of feeling threatened that other writers are better than me, I became strengthened and hopeful for all of us. Which is why I try my best to pull from Tessa's play book and engage with other writers with both praise and constructive criticism/debate.
I wish you all the best as you continue forward with your journey in writing.