IRC GP-1 Trials is my favorite, visually it is a clone to the more widely recommended Shinko244.
Not as knobby as some like but gives a smooth sure ride on a variety of off road terrains. Tighter trials like pattern has less voids to let rocks pierce carcass and overlapping tread blocks give a stutter-free ride and continuity of grip while cornering. Knobbies may shed mud better but I didn't like the feel, especially cornering on hard surfaces.
Others will disagree, this may become a spirited discussion.