For critical long-term parameters, I like tests that are accurate and easy to read.
For salinity, which is very important and which you'll be monitoring all the time, a refractometer is worth it. Floating arm hydrometers are poorly calibrated, so it's best to have a refractometer, or a friend with one, to find out whether yours reads too high or too low.
During the cycle, you'll be measuring ammonia and nitrite, but you only really need to know if you have none, some, or a lot. Any of the combination kits will do, like Hagen, Doc Wellfish, Red Sea. Maybe the strips would work too, I've never tried them. Once the tank is cycled, you should never, ever, see any measurable amounts of these compounds.
For me, the critical parameters to test are calcium, alkalinity and nitrate. Nitrate just gives me an idea of how well the biological filter is working. Salifert's nitrate test is easy and accurate.
Calcium and alkalinity are very important for the growth of corals and coralline algae. For calcium, Aquarium systems, Salifert, and SeaChem use the same chemistry, and are all good, but the Seachem test gives the sharpest results, and you get enough reagents for a million tests. I have always used the aquarium systems alkalinity test, but I'm sure Salifert and others are good as well. It's important to get a test that gives you a numerical value, rather than "high" or "low."
