Green arrow or Nightwing

so i want to add another series to my pull list (batman, superman unchained, jla, jl, tmnt, aquaman, all new xmen, batman/superman).

i have read the paperback vol 1 of nightwing and thought it was pretty good.

i love the way geoff writes green arrow in jl and jla.

now which should i add? one or both?

Green has become one of the best comics books since Jeff Lemire came on the title in issue 17, but I have heard that Nightwing has been good. You should probably get both.

BOTH. if not, Green Arrow is better at the moment (since issue 17 by Jeff Lemiere), and will probably continue to be better. But you want the entire series, Nightwing is the way to go. The Green Arrow issues before issue 17 are crap, while Nightwing has been consistently good.