Maxxis Ignitors have been my tire of choice for a few years. I raced them a couple seasons in the 1.9" width but running 2.35s now. Pretty low rolling resistance for an aggressive tread pattern due to ramped center knobs, soft rubber compound that doesn't wear too quickly and grips well on hardpack and loose conditions, and stiffer edge knobs for corner stability. Never felt like these tires were holding me back when racing.