the scene with bridge four pushing the bridge over the gap while kaladin runs up and jumps over, with him in midair jumping toward whoever's looking at the shirt with stormlight coming out of him and Bridge Four written on the front of the bridge and the shattered plains stretching out in the background would be pretty epic imo.
also, you can have the silhouette of the parshendi below. (like it's really just the main image cutting off there but it ends up looking like a silhouette of the Parshendi. I've seen it done before with wolves on threadless but I can't find the pic)
I totally laughed when I read the "I'm wearing your mom" one, I just don't actually have any friends who read this book so every single would be like WTF and then not laugh after I explain because they didn't read the book. Versus, I'd kinda rather have one going for the serious/cool effect because anyone could see that it looks cool, and maybe some of them would want to read it, and if I meet someone who read it we would still have the "Hellz yeah I love that book" effect.
Of course, if you're able to go to a bunch of signings and stuff then the "I'm wearing your mom" shirt would be perfect so idk.