Ammo type may be judged in whatever way you like, but no dissing other ammo type, that's ammo-ist.
Tiers are:
Level 1-10 Ammo Types
Level 11-20 Ammo Types
Level 21-35 Ammo Types
Remember, these tiers are set up my way, so your tiers may not be the same as mine.
My Favorites:
Level 1-10 Ammo: I would have to choose .357 Magnum Rounds
Level 11-20 Ammo: ........ .308, Sniper Rifle is pretty good at level 15.
Level 21-35 Ammo: .45-70 Government, Period.
Energy Weapons: Microfusion Cell
Explosives: Missile
If you don't get the question in the poll, then move on with your business.