I'm gonna start of with one that most people are perhaps already familiar with, Lab Muffin Beauty Science. She's a breath of fresh air in an industry that's so filled with marketing bs. Or as she would describe her channel:
"I’m here to help you figure out what beauty products are worth buying, and which ones aren’t, using science!"
I like Dr. Shereen Idriss. She's a dermatologist who is quite popular, and similarly to Lab Muffin focuses on the science behind skincare. She also has good advice for a variety of skin conditions.