Against Aggro, you want your removal. Armor gain alone is not enough to give you time to play 5 and 6 cost spells. In addition to that, spreading plague is no longer the aggro stopper it once was. The minions aggro plays now are a lot better than they used to be. The removal you want also differs from matchup to matchup. The only definite keeps against aggro are Lesser Jasper Spellstone, Wrath, and swipe. Spreading Plague and starfall can be kept, but only if you can play something before it or if you playing against Odd Paladin, Odd Rogue or pirate warrior. Against mech paladin you want poison seeds. Naturalize helps against them, but the 2 extra cards sometimes leaves you in similar spot as the previous turn.