I've tried both, and I definitely prefer Elucence. About 5 months ago I bought 12 oz bottles of One C and Elucence at the same time -- they both got good reviews, so I wanted to try both. Since then, I've used about 1/4 of the bottle of One C, but I'm now on my second liter of Elucence!!!! One C is nice, and I still occasionally use the Devabrown One C to deepen my hair color. But I couldn't live without Elucence!!!