If you spend enough time on skincare subreddits, you will notice a shift. The ingredient that was once the undisputed king of hydration—Hyaluronic Acid (HA)—is facing a backlash.

Users are complaining about stickiness, "pilling" under makeup, or the dreaded drying effect we discussed in our previous guide.

Enter the challengers: Glycerin, the unsexy workhorse, and Polyglutamic Acid (PGA), the trendy upgrader.

Which one actually hydrates best? We analyzed the science and the Reddit consensus to declare a winner.

The Incumbent: Hyaluronic Acid (HA)

• What it is: A sugar molecule naturally found in our skin.
• The Superpower: Deep hydration. Low-molecular-weight HA can penetrate deeper into the dermis than most hydrators.
• The Downside: It’s climate-dependent. As we know, in dry weather, it can pull moisture out of your skin. It can also feel tacky or sticky if the formula isn't elegant.
• Best For: All skin types, provided you live in a humid climate or seal it properly.

The Challenger: Glycerin

• What it is: A humectant derived from plant oils or fermentation.
• The Superpower: Reliability. It is smaller than HA, penetrates easily, and is arguably the most effective humectant for repairing a damaged skin barrier. It rarely causes irritation and is dirt cheap.
• The Downside: It’s boring. Marketing teams hate it because it’s cheap. Pure glycerin is also very sticky/gloopy, so it’s usually mixed into toners rather than sold as a standalone serum.
• Best For: Sensitive skin, damaged barriers, and tight budgets.

The Upgrader: Polyglutamic Acid (PGA)

• What it is: A peptide derived from fermented soybeans (natto).
• The Superpower: The "Glass Skin" Seal. PGA can hold up to 4–5 times more moisture than Hyaluronic Acid. However, the molecule is too large to penetrate deep into the skin. Instead, it sits on top, creating a smooth, glassy film that seals hydration in and blurs pores.
• The Downside: It doesn't hydrate deeply; it only hydrates the surface. It is also more expensive.
• Best For: Makeup preppers (it acts like a primer) and anyone wanting that instant "glass skin" look.

The Verdict: Do You Need to Choose?

The Reddit consensus is that these ingredients are not enemies; they are teammates.

• Glycerin repairs the barrier.
• Hyaluronic Acid hydrates the deeper layers.
• Polyglutamic Acid seals the surface.

You don't necessarily need three different bottles. The best serums on the market today often combine at least two of these. For example, The Inkey List has a standalone PGA serum that Redditors love layering over their HA serum to lock it in.

Find Your Perfect Match

If you are sticking with Hyaluronic Acid but want a formula that includes Glycerin for better barrier support, or one that avoids the infamous "stickiness," you need to look at the ingredient lists carefully.

We have done the hard work for you. We analyzed hundreds of discussions to rank the best serums on the market. Check out our Best Hyaluronic Acid Serums Ranked list to find the formulas that verify verified buyers actually repurchase.