My picks:
[ul]
[li]COMPUTE!'s Gazette. I had almost every single issue and must have read them cover to cover a dozen times each. To this day I bet I can still give you the answer to every reader question from the “Feedback” column. I also enjoyed RUN. Both magazines are now available from the Internet Archive.[/li][li]Verbatim: The Language Quarterly. This was a magazine all about language and linguistics, aimed at a non-specialist audience. It never officially ceased publication, though there hasn’t been a new issue for about ten years. I recently contacted the editor, Erin McKean, and she said she’s in talks with a university which is interested in taking over publication, so we might see an end to the hiatus soon. (In the meantime I’ve been reading a new full-colour print and online language magazine, Babel: The Language Magazine, from the University of Huddersfield.)[/li][li]Variant Chess was a magazine from the British Chess Variants Society all about games based on chess. It’s where I learned about my favourite gave of inductive logic, Penultima.[/li][/ul]
The Duelist a Magazine dedicated to Magic the Gathering.
of course at the time I was not only a player I also had a game store.
I remember Discover being a cool magazine back in the 1980s. It later morphed into a green energy / politically-left mag. 
What I miss most of all, however, are the electronics hobbyists magazines. I still have some issues of Popular Electronics from the 1970s. Really great stuff in there. It’s sad that so few people nowadays tinker with electronics.