I definitely like it better with him smacking the zombie, it's a lot more interesting. Perhaps a bit more blood and brain matter would be nice though, to give it a bit more impact. If the zombie's a bit decayed his head would probably just explode like a melon.
I'd add a zombie reflection to the pawnshop window, I never really noticed the reflection before, and with the distance it is from the guy it almost looks like someone behind the window. You don't really need to add any colors to make the posters, just pretend you're doing it in greyscale and it should look fine.
Some highlights on the tips of the broken glass bits might make them look sharper.
Some skid marks behind the car would probably be cool.
You might be able to get a cool effect by darkening and saturating all the reds, make them stand out a bit.
The main character's hair could use a bit of work, it doesn't have much volume. The lady zombie's hair is great.
Some debris in the alley would be nice.
The zombie cop's hand could use a bit of work. It's just a weird blob right now.
Great work so far!