@Ricardus I completely agree, although I tend to think of triangle as a pain in the butt because of the scarcity of bits. Pozi-Driv can be driven by either a Phillips bit _or_ a square drive bit, but it drives flawlessly with high torque with an actual pozi-driv bit.
@Ricardus agreed, although I think the important geometry is the engagement surfaces more so than the overall external profile.
@elb Any bit that's conical in shape requires actual force to hold the bit into the fastener. Things like torx and Allen don't require that pressure for engagement.
@Ricardus That's what I'd call them, but I wasn't sure how widely-used that term is. In general, firearm screws have very high-quality cut heads with parallel sides, and hollow-ground fitted screwdrivers can turn them out with little to no chance of slippage.
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko