[Suicide Junkie]

Some types of PD:
-Short&powerful
-long range&weak
-missiles (PD that can be shot down by PDD!)
-One-shot, 1 range, guaranteed hit, 250+ damage "reactive armor" PDC

Useful PD warhead types:
-normal
-Quad 2 shields (vs fighters)
-Phased (vs fighters)

Note that armor-skipping, null-space, and shield-skipping, are not in the list, because of the way damage is allocated to units, and fighter shields are 'normal'.
If you add phased fighter shields, then shield-skipping will become useful.