My TWSBI 580 fountain pen is one of my favourites. It’s not the most expensive fountain pen, but it always starts well, writes smoothly, and the piston-fill ink reservoir holds a LOT of ink. It’s currently filled with the original formulation of Noodler’s Black Swan in Australian Roses ink, a gorgeous dark purple burgundy colour. Planning to swap out the medium nib for a fine one at some point.
The newest pen is a Tactile Turn Mover in teal anodised aluminium, and it is gorgeous. The exploded view shows some of the nifty design, the clip is inset into the top part of the pen, and held in place when you screw the click part in. The grip section has a pattern on it that makes it very easy to hold, much nicer than holding smooth metal. The click is almost silent, and the pen is a nice thickness. I’ve got small hands but I like thicker than average pens. All around this is a very nice pen that went straight into my everyday carry set.
I also have the Bolt, from Karas Kustoms. It takes a Fisher Space Pen refill, and the bolt action is fun to play with. Currently it has the turquoise refill in. The Fisher refills feel like the ink is thicker than a standard ballpoint but they always just write. The Bolt is fun to play with, after a little practice you can operate it with one hand.