I used VMS in the late 70s and early 80s. I started using Unix too, in the late 80s. What was wonderful about VMS at that time, relative to Unix, was that DEC sold a large set of books, the "pumpkin books", which explained everything you needed to know to do just about anything with the systems (there was also an "internals" book). In contrast, at that time, if you wanted to learn to do something difficult in Unix, you essentially had to go find a Grey Beard to tell you how to do it. The internet and Linux changed all that of course, but before that happened learning VMS was a joy and learning Unix was a pain.