Although I was born Jewish, I was ordained as a Zen Buddhist Priest many years ago. Some Buddhists believe in rebirth but, even so, the human body of flesh is not so important. In Asia, most Buddhists will cremate, although some will bury (and some, like many Tibetans, will feed the body to birds or fish!). In my case, I am not much interested in whether there is or is not some future rebirth, and tend to believe that how we live now, in this present life with care and gentleness, is most important. The body is not important.
So, I am happy to be an organ donor or to leave my body for medical research. In the future, I will not need it any more. I have told my wife that I require no elaborate funeral, and she should just have a party where people play nice music, tell stories, have a drink (in moderation), laugh and remember the times together. Laugh a lot. I have a Buddhist group online around the world (treeleaf.org), so please let them know and tell them to “sit Zazen” (Buddhist meditation). Under no circumstance, have a big, elaborate funeral where a hall is rented, a priest of some sort is summoned and a lot of money is needed. Donate money from guests to charity to help needy people. If donation of my body to science cannot be arranged, then please find the cheapest cremation possible (cremation may be required by law here in Japan, where I live). After that, toss half of my ashes under the trees in the back yard, half on a big mountain (Tsukuba mountain) that can be seen overlooking our town. Maybe think of me sometimes when you see the trees and mountain.
But really (it is illegal, so it is not going to happen of course), I would not care if they left me out for the trash pickup with the old refrigerators and broken furniture. What is most important is how we live now, the kindness we do in this world.