i hate lube. there's one that we use when we do stuff that requires some, however. we go water based with a lube called Moist. Moist is cut with aloe vera so it more natural and more organic feeling. it also doesnt bother my girl's very sensitive skin.
most pros always go for silicone based instead of water (glycerin base) and its very slippery indeed but just not organic feeling enough for me. its great for anal, however.
Olive oil is not bad. Pretty good stuff, actually. Women enjoy the taste of it to boot as opposed to some of the other stuff (should their mouths come in contact with it ).