I've got a Waterman I've been writing with for about 30 years (cartridges, I think it's a LeMan 200), about a decade and a half of that daily. I recently purchased a TWSBI Diamond that I have used for drawing but I wasn't thrilled with it, so I have a Kaweco Sport arriving today. It is very easy to get into fountain pens, thanks for the survey of the ones you've tried. My ballpoint is a .38mm Muji gel ink capped pen, and for keeping my work to-do list I typically use a Papermate Flair felt tip, love that chunkier felt tip feel. (For drawing, I've got a lot of pencils and some Microns and brush pens.)