18-8 is the most common, slightly magnetic, 316 is marine stainless? Non magnetic, and it contains molybdenum, stronger then 18-8 and more corrosion proof. Love 316 but it's not as easy to find. Stay away from 304 stainless - it's garbage.
I built my own buss bars. 36" x 2" x 3/4" copper, silicon bronze studs, nuts and washers. Silver soldered. Dog point studs. Flanged SB nuts. Dog point means the bolt or stud has no threads on the tip. Can work in pitch black and nuts thread on simple.I was forced to use silicon bronze. The idiot fishermen would inevitably double nut stack more wires on top of the first ones. They weren't too bright.
Now that the Chin... I mean Chinese are supplying all our fasteners specialty bolts are getting harder to find.