+1 on stock bolts.
For important stuff, I only get OEM replacement bolts so I can be sure they're the right size, pitch, material, etc. They're almost all cadmium plated (not zinc), which lasts longer and the goldish finish looks better than zinc. If you wanted to keep up appearances, I'd use stainless on stuff like the upper radiator support bolts. New OEM bolts will oxidize within days after a snowstorm and salty roads.
The problem I have with non-OEM bolts is that I can't get quality stuff in metric. The local hardware, Lowe's/HD, Autozone-type, and specialty fastener places either don't carry metric or they're such a limited variety that I have no use. Recently, I needed good exhaust flange bolts and the best I could get from Lowe's was cadmium plated standard hardware. They function perfectly, but metric was not available in cadmium or stainless.