SUSY particles are a nice fit, but things aren't looking too good for SUSY at this point. At this point, the name of the game in particle physics is just to pin down the location of dark matter particles in phasespace (mass, interaction strength). Each experiment blocks off a big section of phasespace and says "We're going to look here!" Eventually, we'll find it, and then comes the challenge of explaining it (SUSY would be nice...). Also, why try arguing that it's antimatter? Antimatter has no exceptionally-different properties than normal matter. Saying "it's antimatter" is kind of like saying "it's matter," which is kind of the trivial solution--either way you're going to have an antiparticle for whatever it is you find.