I don't use fountain pens, as I find them too scratchy in general, and the smooth fine nibs kind of defeat the purpose IMO.
I do however have a Tactile Turn Mover (in Ti), a Karas Kustoms Retrakt, Uni Jetstream Oily or Prime (a japan only version that is pretty amazing), and I always have a Sarasa Grand with either a Juice UP 04 or Energel LRN5 refill depending on mood in my Leuchtturm loop for work.
I'm a big fan of high quality retractable gel pens and pens that can take Pilot G2 sized refills. Gotta be retractable for work!
For parker style refills, I actually have a Parker XL with the OHTO Flash Dry refill. Absolutely the best fine tip refill for Parker style hands down IMO.