Interesting. I don't collect but i do calligraphy and use a fountain pen as my main instrument. I use a noodlers Ahab primarily because of a flexible nib. I used a Waterman for a long time till sometime I lent it to dropped it. I also have a Lamy gifted to me it. It's good but i prefer a narrower nib.

I concur with your point about the ink. I used to use private reserve but recently shifted to Waterman and I'm happy. I prefer the colour of the later. Another important thing is the paper. It needs a bit of a bite that produces a scratchy sound. Also, older paper that's exposed to humid environments tend to bleed the ink causing bad writing.