Question

according to law of conservation of energy and biological magnification and 10% law which food diet is better

Answer 1

We should have vegetarian diet as it directly comes from plants and not from animals

If we have non veg than we are at third or fourth trophic level and energy we consume reduces
But if we have veg than we are at second trophic level and energy we will get will be more

Answer 2

Vegetables are better, because they are natural also according to biological magnification if we eat vegetables, we are on the second tropic level which will have less concentration of chemicals to us. According to 10% rule, if we eat vegetables we get more energy because most of the energy gets removed if we eat as third tropic levels(through vegetarian animals), we can't get more energy.
So vegetarian gives us more energy and harmless. Moreover god gave us everything only to eat.
Hope it helps!