I won't claim one method better than the next...In my experience, which isn't a whole lot of clutches, I've only used vermiculite. I don't weigh or measure anything...really just eyeball it. I prefer to go a little more on the wet side than dry side, and the eggs can handle a little bit of excess moisture just fine. If I get too much condensation on the inside of my box, I'll add a little more vermiculite. If the box ever starts feeling lighter, I'll add a little more water.