My first and favourite pen, like Len, is the Parker 51 and I not only collect vintage 51s but also custom 51s and make up my own 51s from parts.
This is a Cartier aerometric from the 1950s, bought from Stephen Overbury off the Green Board and a certain keeper:
I have collected a lot of Classic Pens editions, have sold some but have kept a core collection, amongst which is one of my first, my ZJ1, heavy silver, custom stub nib:
I have only two pens by David Broadwell but I love both of them; my first, this "Plume" in Damascus steel with a Richard Binder cursive italic nib:
and my second, the steel "Chrysler Building", perfectly engineered, minimalist, tough: