lol, I was at one point recommended the tetra test kit. The cheapest thing ever, but the guy who told me once said he tried them all, and even tho it's the cheapest its better than most.
Now I have not tried it, nor am I a regular water tester, but just pointing out that a lot of times it really comes down to what you feel comfortable with. Plus, most of your testing is to get an idea of where you stand. for example, you can take your water to einsteins and get a full elos panel for $10 if you want to see what one of the most expensive sets reads, and then test it against api at most any other lfs for free.
I think it would also be best to spend your money on the things that matter the most to your system. for me I cannot keep my ph right at all, so I buy the easiest to use kit so I can do it more regularly. Nitrates are not toxic below 10ppm, so I'm not interested in paying extra for a kit to tell me I have 2ppm. Calcium is a pita to test for in all the kits I've seen so I just take a sample to my lfs every now and again to verify I'm not doing something stupid. Ammonia and nitrites are almost always 0, but are important to look for, so I use a multi-strip. An aweful choice I know, but if it reads anything other than 0, I'll take it to a lfs to verify because I think any of those 2 test kits would expire before I'd be able to test my water a couple times as needed you know?
