In most things I tend to stick within one brand, but find with test kits I naturally gravitated towards different test kits for different parameters based on ease of use and time required.
That said, I run a mix of Salifert, Red Sea, and Hanna. I started with Salifert NH4, NO2, NO3, Ca, and Mg because they were the lowest priced and considered accurate. Those will be just fine for initial testing of a new set up and take you forward (I rarley use the NH4 or NO2 test kits anymore, probably been a year or more). The Salifert kits don't come with as robust a setup kit as Red Sea, you will feel like you're getting more with Red Sea; i.e. hard plastic box, color wheel, etc. Salifert comes in a cardboard box with the reagentss, test vial, a color card, and a syringe. I end up tossing the box they come in and putting the contents and instructions in a 1 quart freezer bag, and write the directions on the bag with a sharpie. Doing that also saves space in my test kit bin.
I picked up the Red Sea Nitrate Pro NO3 test kit because it tests at very low levels. I use both that and the Salifert, especially if my nitrates are running a little higher (above 10 ppm). For NO3, the Salifert test takes 3 minutes, vs 9 minutes for Red Sea. The Salifert can easily change from low value readings (read from side of test vial) to high value readings (read from top of test vial). The Red Sea NO3 kit requires an extra step of diluting the tank water with RODI water if you are above about 4 ppm. I think BRS did a comparison, and when you go for refills from Red Sea (the only brand that sells refills, I think), it is cheaper over the long haul to go with them.
All that said my line up is similar to what you chose.
Ph: Apex
Salinity: Apex and refractometer
Alk: Hanna Marine dKH checker; too easy and fast. I test almost daily
NO3: Red Sea Pro when my nitrates are stable and lower, for a while they were almost unmeasurable. Salifert if it's higher or I don't feel like waiting 9 minutes for a result. Test weekly/bi-weekly
PO4: Hanna Phosphorus ULR checker. Not as fast as the Alk checker, digital readout makes it easy to read. Note that it gives you a Phosphorus reading in parts per billion that requires some quick math to give you your phosphate (PO4) reading. Test weekly/bi-weekly
Ca: Salifert. I will probably try the Red Sea Ca test when I run out of reagent. Test weekly/bi-weekly
Mg: Salifert. Same thing as above, will try RS when I run out of reagent. The color change on this one is more subtle than the Ca test. Test monthly/bi-monthly
NH4: Salifert. I haven't tested in more than a year. Mostly for cycling a tank. If I had a big die off, bio load dump, or the tank looked bad I'd test again.
NO2: Salifert. Also haven't used in a long time.
Just one opinion of many. Good luck!
I think any of the tests would suit your needs, just depends on where you put your value level and what tests work for you (and you'll actually do).
