Salifert are as good as it gets imo, If you want super accurate results then you need to spend 1000's on lab grade equipment.
But as hobbyists a ball park figure is ok. Don't go chasing numbers as it will drive you crazy and not good for your tank, stick to the same test kit for each test you do, lets say your kh test kit is 0.5 dkh out, if you use the same test kit it will always be 0.5 dkh out so its consistent and stable, stability is key to any tank not numbers. Your tank is the best test kit on the planet, if it looks fine then keep doing what you are doing.
Hanna test kits are no more accurate than salifert really, the only advantage they have is a digital readout, which is good for people who have sight problems, other than that I see no other benefit too them. Plus they do not have a great margin for error, such as the test vial must be absolutely spotless or it can skew the result as can many other things with the hanna.
