Correction - damage spams are the way to go when your enemy only sends armor spams.
I like to make 2 types of spams. the normal spam - 1 armor inf; and my anti spam; 1 armor inf and 1 ranged inf
i usually just call my spam suicide lol. it's really only meant to gain quick territory before my enemy can react and to get intel on enemy units. my anti spam is what keeps my OPs from getting taken by spam and to cut off spam. I usually have about 10 anti spam made and on multiple different gates at all times.