It's really a matter of taste. Batman Inc is definitely better than Morrison's Action (I've been on the verge of dropping it since #3). However, as many people have said, Inc. is only 12 issues (with Morrison anyway) and will be the ending to his multi-year story that began in Batman, Detective, Batman & Robin and the first volume of Batman Inc some time ago.

So if you're liking Action and Batman right now, I'd just stick with those and maybe get Morrison's Batman stuff in trade if you're interested. That's probably the easiest route.