As a Sang I fed from humans, properly -*test*-('")ed and clean humans of course.
Everyone who is responsible understands that both the person giving the blood and the person taking the blood must be clean and have been -*test*-('")ed to ensure it.
As a Psi I never have taken directly from the energy of a human. And the energy they 'give off' has too much of the feel of a waste product to me to give me an appetite.
I prefer clean energy like storms, gales, even sunlight when filtered through a Crystal. Though the BEST energy comes from the local nuclear power plant.

I also agree with Zygo that even if
we find feeding from these natural sources to be much better, if no-one else is ready to listen we would be wasting our time trying to press the point. Mention it and see how it is recieved, and if more information is requested then go ahead, but if the idea is rejected then instead of trying to force them to accept what we say as a good idea, then we should back off and wait until the time comes when they are ready to listen. Forcing your ideas on another never has a good outcome, even when your intentions are good.