My favourite pens are definitely the ones made by Lamy. I've three fountain pens: silver, blue and yellow; a black rollerball; and now a propelling pencil as well. I love the shape and feel of them. I also love my two italic Rotring calligraphy pens (don't think they are made any longer), and I have three beautiful Waterman tortoiseshell enamel pens, one green fountain pen, one blue fountain pen, and one rollerball.
Favourite ink colour in some way relates to the background colour of the paper being used: I find average ink pretty insipid, but the range of colours in my ink drawer includes ebony, three shades of blue, emerald, red, purple, plum and brown.
And this isn't anywhere remotely near to the area of my obsessive interest! I think I might be Aspie.....