I learn runoff from the IBM and the TOPS, then PUB then Scribe before I saw the nroff/troff family.
I have fond memories of using Scribe (which was sort of the model for the LaTex macros when it got tied up in the legal entanglements of CMU). So UNIX was what I had and became adept at it.
Like Larry, it's still my goto today and even prefer to Word for anything over a single page.
For some reason I prefer the MS macros, probably because I learnt them
first and I find it difficult to use MM.
The order I learned them was -mm {PWB}, -ms {V7}, -man {V7}, -ms {Tek}, -me {UCB}, -mS {MSCP}, -man {UCB version}. I feel into -ms with a couple of macros from -mS (.Li/Le for lists which were similar to MM's) for big documents, and the UCB -man for really simple things. It becomes a 'less is more' sort of thing - -mm and too complicated and I was not writing BTL tech memos, and after I did not my thesis, I did not need Eric's work (which was perfect for a UCB thesis).