I like the last one (your efforts and your rewards). I'd buy it anyway. Is there some technical difficulty in just having all of them? I guess this isn't print on demand, right, you would have to stockpile T-Shirts in case someone ordered one of the less popular versions. Still surprises me in these days of automation you can't have a bunch of blanks with "your phrase here" a la the M & M campaign. I'm sure you can, but production cost would no doubt go up.
I think whichever is the winner, Catbert's title should be there, "Catbert, Evil HR director", rather than just Catbert. None Dilweeds might not get the joke otherwise.
"Evil. Made from concentrate."
"Somebody's got a case of the Evil"
"667. Because I'm even more evil than him."
"The evil baby...you know you want it."
"Evil and unrepentant. What did you expect? I'm a cat!"