Menacing spikes and enormous corkscrews penetrate armor well and rarely jam. Glass isn't very heavy, so spiked balls aren't a very good choice. Serrated discs work well vs the unarmored bits, and I imagine a giant axeblade does fairly well too, but I don't use those.
My typical fallback, however, are silver/copper spiked balls, considering how common those metals are. They soften up/kill pretty much anything, rarely jam, and allow my military to kill them more easily, giving them joy from slaughter and making them battle hardened.
the axes kind of suck. most are deflected by clothing it seems, but on an allready injured target, i've seen them lop off limbs. disks are overall better, they hit more often and have three attacks to the axe's one.
the axes MAY be able to retain more damage against large targets... in some situation where the best a disk can do is cut the fat. i havent had any of those make it to a trap for me to test.... only trolls and ogres, and disks work fine on them.
i'm just a fan of variety.
in passing, i have two external weapon traps, stocked as i described before. behind these traps are two windows. when trolls and ogres show up with the goblins, they make a beeline to the windows, and often-times, the entire group of trolls/ogres is destroyed by my two traps. they've jammed after about half of the building destroyers have been dealt with, before. either way, it's a lot better than facing ALL of the them.
oh, and a last thing about my exernal traps.... behind the windows, is the moat of my tower. sometimes, an enemy passing over the traps will end up dodging into my moat and drowning.