I preferred Halo's single player. COD single player fails to capture my interest. But I use to like COD online. But I am done with online shooting fest. Five years is enough for me.
I think one reason Halo 4 stood out to me is because it surprised me. I liked Halo 1 and 2. Hated 3, ODST, Halo wars and reach was ok. But when I heard Bungie was for the most part not touching the product I was almost certain the end product would be disappionting. For fans and new comers alike. But someow they pulled it off while improving the campaign experience by making it more cinematic and grand in scope. While call of duty black ops dos did nothing new really. It took the safe path whih isn't always bad...but after many call of duty games I felt the formula needs to be improved and refreshed outside of chaning the HUD's appearence.