I use the 5 pad dip strips for quick checks, and have a liquid reagent kit with all the tests (gh, kh, ph, ammonia, nitrite, nitrate, iron, and a few others I don't remember) to check that the strips are accurate enough.
If you get a liquid kit read on there for an expire date and make sure it isn't past or close.
Strips aren't always very accurate, but they sure are convient as an indicator if you want to do the liquid version of the test.