I tried stainless as I typically hate black oxide (rust), but didn't like the contrast against the black fuzzy material. I ended up with the black oxide flange-head SHCS with black nylon washers and a nice ball-end hex driver that I keep with the top. Those rear flappy-clamp bracket things bother me (they always catch on something as I'm pulling or installing the top) so I didn't even bother turning grooves into the screws, I just take them all the way out and remove the brackets completely. Soo much easier.
(Until of course you drop a screw under the passenger seat!)
Have you ever used the 'black oxide' stainless? McMaster doesn't have it in this size, but wondering if it has the benefits of not rusting while still being black..
I agree on the material / screw choice being terrible, along with Torx being a bad choice for those rear bolts. Mine were so stripped when I got the car it was nearly impossible to get them out. Nothing wrong with a little OCD!