I love good documentation.
The Rover P5's workshop manual - the original one written by the engineers at Rover - is the best manual I have ever used. I especially enjoy that the manual sets out exactly what tools you will need including the sizes of spanners in the preface. This is the only workshop manual I have seen that does this, and it makes every job a tiny bit faster and a tiny bit more fun.
How many times did I work on the Mazda and read through a 20-step walkthrough and then in step 19 it says "use special tool, part number F-U, which is obviously completely unavailable for any amount of money to remove this delicate thing that will definitely break if you try to use cruder methods to remove it"?
Good documentation is important, and I believe in thanking people for good work even if I am late to their particular party. So, thank you, Rover engineers from 60 years ago. You did a fantastic job.