Definitely both. What would really compliment the 2D editor atm, is to make suspend take us straight back into the editor UI. Without having to manually go back in there. Then, in my eyes, a 3d editor becomes less important. Since the main pillar of the 3d editor is the ability to precisely place objects. But, if I can transition into & out of (into the mission) the 2d editor very quickly & seamlessly, then precise placed objects via 3d editor become redundant. Since the 2d editor is quicker to work with (once you're actually in the editor).
Regardless, I'd still like to see both