Define "quality". What specifically are you looking for? A certain level of resolution? Accuracy? A high price tag that makes one assume the test must somehow be better?
API has worked fine for me. Resolution can be enhanced by doubling the volume of water under test, in which case each drop of test reagent represents 0.5 GH or KH. They are accurate, but the GH test in particular is untrustworthy if used past the expiration date marked on the bottle.
It's more important to learn caveats like these, and how to verify test kit operation by mixing calibration solutions. Any test kit can fail, regardless of price or perceived quality. I once spent $40 on a test which API sells for $6, only to find it completely failed. And so did its replacement. Thank goodness I verified it against calibration solutions rather than trusting it based on price.
I have a white mug that is pretty small. I pour 10mL of aquarium water in that and use the gH test kit from API. The white mug makes it MUCH easier to see the color change. Using 10mL for 0.5 degree resolution like previously mentioned.