I have lots of HANA colorimeters and refactors: lr copper (ppb), iron, phosphate (ppm), alk (dkh), cal, ulr nitrite (ppb), saltwater refractometer. I love them all mostly because I hate judging colors, but in terms of most used: Alk, Cal, phosphate, iron (i dose iron, if you dose it test for it).
Many people didn't like the calcium colorimeter. My understanding is there was another version which did not include the micropipette and was just a plunger. Personally believe it does a fine job. But completely understand why it would be an impossible test with a plunger vs the pipette.
I also greatly appreciate the temperature compensation with the refractometer, it gives me great confidence that all may tanks in the house are in alignment and not just some fuzzy blue/white line reading... When the wife is taking care of mixing water or anything I trust her results a little more
If I got to do it again I would get the ULR (ppb) phosphate colorimeter, it would be more useful than the normal range one that is ppm, same with iron, it would have been better to get the LR that is ppb.