(Sorry for the huge delay!)
Personally? Something like your signature, the buttons on the comics page (Nyte being all "WTF?" over the pink shirt, all the way to "you" teasing Narya behind a tree), or even the banner up here on the forums (Miji riding his kitty mount 2.0?), or... idk. TBH if I had to pick one of those three, Miji on his cat would be my personal choice.
Or hell, you could take occasional polls or suggestions asking the fans what they would want to see on a shirt next. Whatever happens, I WANT to see it succeed
I do like the clones, but I feel like they themselves, plus explosives usually used in wars, doesn't really 'feel' DLC to me.
Regardless though, when (not "if" because I KNOW you'll get this going
) you have more T-Shirt designs, I'll totally be here, card in hand, ready to say "SHUT UP AND TAKE MY MONEY!"