follow through and overlapping action is hands down my fave principle. u can skip the main animation and still make it read fluid with this principle. talking about fluids, i love animating FX so...straight ahead is a strong second choice..:D
this is so cool giveaways! i love to participate. My favourite animation principle is Secondary Action supporting the main action with secondary one adds more dimension to the character animation and gives a scene more life. Giving more life to animation really matters.