For manual test tube style kits, I too find Salifert kits to be the most accurate available. However, I have had good results with the API Reef Master Test Kits and Salt Master Test Kits. The test tubes are a bit flimsy - but even if you buy additional tubes the cost of the kits is very inexpensive and I find them easy to read and relatively accurate (except the phosphate test - which does not provide a low enough range in my opinion).
Unlike others, I do not like the standard Red Sea test kits. They seem less standardized to me (some use 6ml of tank water, some 10ml, some else) and I find them difficult to read by looking down through the tube as opposed to the side of the tube like API. Red Sea does offer a professional series of kits, which are priced similarly to the Salifert. Thus, I haven't tried those yet as Salifert has been very reliable.
Just my opinion. All the "reef specialized" kits available today will be relatively accurate and similar to use. Avoid kits not made specifically for reef/marine environments.