this would be my first choice, honestly.
Any type of incineration and just let the ashes return to the earth.
Liquefaction would be fine to if they find a natural method like an enzyme or something but i don't want my body being part of a poison chemical stew after.
Burial would be my last choice. First off don't get the entire embalming and put in casket thing. That is just dumb to me. But I would be ok with just digging a hole and throwing my body down in it and leaving it as worm food. As long as you do it deep enough that animals wont dig it up.