I would like to be purreed in a large blender.
If my family can't find a blender large enough, they can chop me up into smaller pieces to puree in small batches. Then I would like my human body slushy diluted with water and taken up in one of those fire fighting airplanes that carry lots of water and have the slushy dropped out over a pristine forest of trees.
The way I figure it, if I am burned, all the nutrients that I spent all these years creating are destroyed. If I am put in a metal lined box, all those good nutrients are isolated from the ecosystem.
The only way for me to live on in this world is to have my nutrients taken up by trees as fertilizer. That way, if I am lucky, I can end up being a leaf at the top of an awesome tree. Or I might travel around in the biosphere as part of lots of flora and fauna.