Well, as Grant said, everybody has their favorites. What I would recommend, and I use them, is the Aquarium Pharmaceuticals Master Kit for FW
. This has everything you need for basic testing. They are fairly easy to use. I have compared the results of these tests to other kits and they seem to be accurate. It's a good starting point anyway. Be warned though, that the ammonia kit will not give an accurate reading if you are using ammo lock or any other product that binds ammonia.