We all do our best to keep our skin in tip-top shape by diligently cleansing and slathering on anti-aging products. The next thing on our wish list? A vitamin C-packed serum to brighten our visage as fall approaches. We've been known to sift through thousands of reviews in search of the perfect product, but honestly, this can get pretty exhausting. Luckily, our friends over at Rank & Style have found out exactly which vitamin C serum packs the biggest punch. The site uses customer reviews, editors' picks, and overall buzz to figure out which products are going to work the hardest for you. Consider its authors beauty lovers with a penchant for math. After crunching the numbers, Rank & Style named Skinceutical's C E Ferulic serum the winner for its rave online reviews and popularity among editors and consumers alike. On Skinceuticals.com, user Alissaw43 wrote: I don't even care how expensive this serum is — it is sooooo worth it! This product has changed the tone of my skin. I have not seen any age spots appear at all since I started using this. [It] protects my skin from the sun and environmental stressors. My overall skin tone has improved, and my fine lines are less visible. I only use this product in the morning. I will alway be a Skinceuticals fan. My skin is combination/sensitive and this serum works well with my skin type. Definitely would recommend it to anyone! I'm almost 30 and people always think I'm a teenager! We're not at all surprised that this product is the reigning champ where vitamin C serums are concerned. You'd be hard-pressed to find a beauty editor who hasn't fallen head-over-heels in love with it — and for good reason. Its antioxidant-rich formulation protects against free-radical damage while immediately brightening your complexion. We already know it's going to be our skin savior as the temps start to drop this fall.