The Paula's Choice 8% AHA Gel Exfoliant is the second Glycolic Acid product I have tried, the first being The Ordinary's 7% Glycolic Acid 'toner' (which is a misnomer – it is an exfoliant). I personally prefer the PC over the TO, though both are stellar products in their own right.
The Ordinary's Glycolic Acid product has its perks. It is more affordable than the PC product, for starters. It comes in a much larger bottle (240ml vs PC's 100ml), and it has a longer ingredients list that is full of skin-restoring amino acids, proteins, sugars, natural moisturising factors (NMFs), and anti-irritant plant extracts. The PC product does have some of those, but not as many as the TO product.
On the other hand, the TO product has a high amount of fragrant rose water, which may or may not be okay to use on a frequent basis. I am also not a fan of the watery, runny texture, but PC's BHA Liquid, which I use frequently, has the same consistency, so it would not be fair for me to disparage the TO AHA on the basis of its consistency.
I still prefer the PC AHA, even with its added expense, because it is marginally stronger (at 8% vs TO's 7%) and its gel-serum texture feels absolutely luxurious, making it a dream to apply. The gel has a nice amount of slip (achieved with no silicones in the formula) and great spreadability. I also enjoy its fuss-free pump dispenser (a pump dispenser is always a bonus).
At the end of the day, the PC and TO AHAs will do the same thing. They will both exfoliate and brighten your skin. Neither product is 'superior' to the other – they are both some of the best OTC AHA exfoliants that your money can buy. Choose whichever one suits your budget and your textural preferences.