In case you want to run an asymmetric tire setup, you should put the tire with more traction up front and the one with lower rolling resistance in the rear.
Vittoria is the correct choice. They roll fast, knobs or no. Front or back. In fact I have Terrenos (smooth center, chunky shoulders) that I might put on.
Check out the WTB Resolute if you have clearance for a 42 and mud. Those have been a reliable choice for me - they have enough knobs to handle the slop but they still roll well down the center.