I'm just the opposite. I LOVE the Argan Oil but I don't like the Olive Oil as much. After I finish my liter bottle I probably won't repurchase the Olive Oil one. The Olive Oil formula doesn't keep tangles away as much as the Argan Oil, and, on my hair, the Argan Oil formula seems to retain more moisture. The Olive Oil one leaves my hair feeling very dry after my hair finally completely dries. With the Argan Oil formula, I stock up on the liter bottles! The Argan Oil formula ignites my curls, and it really controls frizz and makes my hair so soft for days. It feels and smells fantastic.
-However, I wouldn't recommend it outright to anyone with sensitive skin, because it's super tingly and cold-feeling (which I love).-
I also have the Sweet Almond Oil one, but it's not nearly moisturizing enough for my hair. I wash my 4 year old daughter's hair with the Sweet Almond Oil, and it's wonderful; no tangles or knots! It leaves her hair super shiny. (If I use it on myself it's to shave my legs, and it's great.)
I have yet to even try a single Wen product! Can you believe it? One of these days I'll spring for some, but I can never figure out if I should try Fig, Lavender, Tea Tree...for the ridiculous price, I don't want to buy the wrong formula. I can't imagine it working better than the Hair One Argan Oil, but maybe that's just wishful thinking.