That's tough, because I think that I would agree because of the sheer amount of stuff on Netflix, but I think the quality of HBO's original programming is far superior. The thing is with films HBO gets bigger ones, but generally blockbusters, while there's still a higher chance that smaller things would show up on Netflix, which makes that more appealing.
Though I watched War Dogs on HBOGo the other night. It was cool to catch up on something I would never see in a theater, but was curious about because of Teller and Hill.