The Monthly Review

I don't have specific suggestions since Monthly Review has already been mentioned but I would probably take the approach of singling out a particular academic like Taimur Rahman, Radhika Desai, or Vijay Prashad (I didn't mean to single out theorists from the Indian subcontinent but there you go...) and see where they get most of their academic stuff published. Usually these figures have a personal domain which lists their published articles or if they're attached to a university you should be able to find a list of their published works on the university profile page for the person in question.

I'm not sure if you're looking for an academic journal for the purposes of institutional study or if it's more about the calibre of writing. If it's the latter then there are a few sites that might be worth taking a look at - Prashad's Tricontinental, Red Sails, Friends of Socialist China, and maybe the Critical Theory Atelier if you want some post-postmodernist stuff.

https://www.scienceopen.com/hosted-document?doi=10.13169/worlrevipoliecon.11.4.0428

http://en.qstheory.cn/latestissue.html