I haven't even read it, but I voted for it: Green Arrow. Jeff Lemire is a killer writer, he's bringing the character back to his gritty, street level roots, and Sorrentino's art looks amazing. I'm willing to bet that it'll reach the top of my reading pile when it's released.
I had read both Stormwatch and Grifter. I dropped Stormwatch because there were better books out there and obviously Grifter got cancelled. I would go with The Grifter with a good writer attached off of that list. From the ones I haven't read, I would likely go with either Deathstroke or Green Arrow.