For MTB 26" (ISO 559) the fastest tires are Conti Grandprix and Schwalbe Stelvio. Both are built just like performance road tires (700c) but in sizes for MTB (26x1.0). However I wouldn't use either for commuting. I don't think the Fatboys are tough enough for commuting either. My personal preference is for Marathon Slicks 26x1.35 for commuting, however I do run Stelvios on longer rides. My commute just has too many obstacles and debris to trust the light weight tires.
Craig