Sure, it would be easy to just pick a Single Second shirt (Chthonic Triad), but I wont.
I like t-shirts that are either weird, will offend people or will get people thinking, a combination of all 3 is obviously the best.
It is impossible to remember all of tees that came out in one year, so my best one is the one that I remembered the most and stuck in my head.
Actual Pain: Goathead
This shirt is all 3 of the above, it is weird, will offend some people, and will for sure get people thinking. I love it!
A very close runner up is.
Black Scale: Twin Towers
Guaranteed, this will offend some people and make people think/remember that day. I dont have to live in the US to appreciate this shirt.