Hm...Probably Carriers, because they're pretty unstoppable if you place them right. For zerg I'd say zerglings, and terran would probably be goliaths or siege tanks.
I also played in a Phantom game where the supply limit was changed to 400. Now imagine that many battlecruisers with +30 upgrades. It was fun
haha, ive massed zealots before too, and reavers, now that was a pain, corsairs were pretty funny, i usually dont mass carriers because they max maps fast and lag ALOT