Editor's Pick! This Ghost Democracy hyaluronic acid serum is a favorite of GH Beauty Lab senior chemist Sabina Wizemann, who has sensitive skin. "It has 2.1% HA, one of the highest concentrations I've seen, and 4% niacinamide to strengthen the skin's barrier," she says. "I found it to be an excellent base for a moisturizer and noticed my skin looking a little plumper." Plus, "niacinamide tends to irritate my skin, but I haven't noticed discomfort from this," Wizemann notes.