They are both very good. I use the Red Sea and it seems easier to,use. I just got the combo kit with the calcium today and it was super easy and accurate. The titration thing is very cool.
Also, was talking to Francis from fish tank kings at my Lfs
today and he mentioned that the tropic Marin kits are good and what he uses. I might get that for ammonia and ph when I am finished the API ones I have now.
For the price, the Red Sea is the way to go.
Unless you have an issue with silicates, skip them.
Also, skip the copper till you need it. You will be picking up copper meds and can get the test kit at the same time. I do however recommend a QT tank. I learned the hard way and have a 200.00 Australian tusk I am currently treating for iCh 😕