Lav's also have a tendancy to fluctuate with the talent, creating a ruffling sound.In static situations like interviews or people sitting down at a table or something you can disguise the Lavs pretty easily, and the wireless ones especially, and they even give off very nice sound, but really your best bet, overall is the boom. The boom will deliver unidirectional sound or even wide if you want, and although it is a pain to use a boom pole and boom, as long as you can see what you are framing, and especially if you plan to letterbox, the boom is quite easy to hide. But just remember you need to get the boom real close to the talent, as close as you can.
As has been said, DO NOT USE THE IN CAMERA MIC. In situations where there is little sound happening in a scene, just dialog, the noise pickup is terrible. I did only use the in camera mic for TSP, and suffice to say, NEVER AGAIN.