Hands down....jojoba oil. Amazing stuff. Use it daily as a cleanser and a moisturizer. Will not clog pores or create zits, actually quite the opposite.
And if you want something that is not "one ingredient" but is the best cleanser I've ever used, go to
http://www.skinactives.com
and check out the Salicylic Wash. It's the same acid found in aspirin. Amazing stuff.