[Routine Help] If I had to choose just ONE active to use in the morning, should I go with Vitamin C, Niacinamide, or Azelaic Acid?

Beauty Tips For Body Care
Mostly I'm looking to reduce hyperpigmentation and improve texture, as well as prevent new breakouts. I have oily skin that's not easily irritated. I'm currently using .1% tretinoin nightly and of course obsessively using sunscreen. I'm looking to add another active in the morning to complement this. I have heard great things about all three, so I'm having trouble choosing just one. To those who have experience using them, which have you found to be most effective? Also, which is the best to use while on tretinoin? Any advice appreciated, thank you.
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Submitted by derserph