Rapidograph for several years--to the point that I have gone through many of them. If you don't use them regularly, they go to the dogs. I've tried using cleaners etc., but it's easier for me to just buy a new one! I do love them because unlike marker pens, they keep on going even when writing over paint and other media. My Pitt/Micron graveyard is populated with pens that died within minutes of use.
Recently I read about the Lamy Safari pen with a special ink converter. I like the idea of this fountain pen because it uses cartridges. However, to get the waterproof ink I need for wet media, I purchased the highly recommended Noodlers Bulletproof black ink.. It bonds permanently to paper with cellulose and is nice and inky black. To use your own ink, you'll need a converter to replace the cartridges. Filling the converter is worlds easier than filling the Rapidograph cartridge. For that I am thankful.
Between the two pens I find differences. The Rapidograph has a round nib with nice ink flow, but it's scratchy when I write on watercolor paper (which I usually do). The Safari flows more smoothly on paper, but it binds up when fibers get stuck in the nib (which they usually do). So it's helpful to have both and switch, depending on what I'm drawing and whether I'm going over paint or drawing on a completely virgin surface. (I'm not writing on *actual* virgins--this should be noted.) I thought I'd put up a mugshot of the culprits I use for daily sketching and such.
And about the drawing...it's a concept I have for the wall behind our bed. I want to paint it directly on the wall. The asterisks were Bill's idea and I've latched onto them as my thought and speech bubble contents. They are silly and perplexing and perfect!