My vote goes for the Fisher. After having a regular pen blow up on the console of my truck just about every summer I got one as a gift. Haven't had a blow up since.

Fisher space pens also makes refills that will fit a lot of pens.

I got a couple of the skinny, break to fit refills and a piece of 1/8" I.D. stainless steel (brass is easier to find and works just as well) from a hobby shop and made my own small pens. I broke the refill to the size wanted, cut the tubing to the same size and epoxied the refill in the tubing.

I kept breaking the tip off of the golf pencil in the Ritter PSP everytime I carried it in a back pocket. I made one the same length as the golf pencil and replaced it. It is MUCH skinnier and goes vertically into the PSP instead of horizontally on the bottom. You don't have to dig everything out to get to the pencil. I put a wrap of orange vinyl used by sign makers to give it a little grip and make it more visible. Yellow duct tape would work just as well. Beautiful little upgrade!