"Everyone I know uses API. None of they have complained about it being inaccurate, most of them love it."
I uses JBL PH test kit, Nitrit NO2 test kit, don't know what brand is that for the KH test the shop ran out of JBL test kit.
And API test kit (The cost almost the same as the JBL) but API can test more. Here's my API Ammonia test kit
Well, i think those product are good indication of the water quality, just look how happy my fish swim and no longer photo shy i knew the kits interpreting the correct condition of the water.