I recommend the "mixin' it up" playlist. In this playlist, you must complete 3 missions: Sierra 117, The Storm, and Cortana on Normal. Should take an hour.
"Wheels, Wheels, and more Wheels" is also three missions on normal, but those are longer missions. Might take an hour and a half.
The "easy campaign" playlist will take much longer, but is a good place to work on other achievements.