Matching the color of the test to the color chart can be frustrating with API test kits and salifert can seem a little intemidating for a beginner. That being said I've used API for years and once you learn that the colors don't exactly match they are a good test. Salifert is a more accurate test imo but takes longer to test and costs more. One thing to keep in mind is that all the test kits are "hobby grade" and within the same tolerances so unless you are willing to buy pharmaceutical grade tests expect a margin of error.
I use API for PH, Ammonia, Nitrite, Nitrate, and Phosphate
And Salifert for Calcium, Alkalinity, and Magnesium