I would prefer if both campaign and multiplayer were good. The wording on the poll makes it rather limited and extreme. But anyway, I really like a good campaign. Multiplayer might last longer, but the nature of online gaming communities can greatly subtract from experience. Aside from that, campaigns usually offer a deeper experience than multiplayer, which is normally focused on challenge and competition rather than story, narrative and the likes.
P.S.
In the end, my real vote goes for variety. I'd like to have games of all sorts, some with great campaigns but weak multiplayer (and if it's weak it might as well not be there at all), and others with great multiplayer but weaker campaigns. I enjoy campaign-centric games like Half Life, Bioshock and the likes, as well as multiplayer-centric games like Team Fortress 2.