Spartan Chess. Because I like end-games, and Spartan-Chess end-games are always an interestig battle, because they always have unequal material. Since the only pieces that white (the Persians) and black (the Spartans) have in common are the Kings, the only symmetric end-game can be bare King vs bare King.
A more exotic Chess variant, specifically designed to give interesting end-games, is Team-Mate Chess. No single piece has mating potential there.

Shogi seems to be too chaotic to be fun.
Less popular chess variants may be fun but because so few people play them there is less incentive to play them regularly.