The best vitamin C serum depends on your skin type and budget. Popular effective options include SkinCeuticals C E Ferulic for luxury, The Ordinary Vitamin C Suspension for budget-friendly, and CeraVe Vitamin C Serum for sensitive skin. Look for serums with 10-20% L-ascorbic acid in dark bottles. Choose stable formulas with pH between 3-3.5 for best results.