I agree with Left C. I have used both, sometimes side by side for comparison. If anything, I have found the 5 in one strips to be MORE accurate. The PH reading on my strips is consistently 7 to 7.2, which is in line with the local water department's information. The PH drops and test tubes kits has read off the chart on the "low PH" test, and different every time on the "high PH test."
The strips are faster, less labor intensive. Less mess if your cats decide to jump into the middle of everything to see what you're doing.
IMO, you should just have the drops and bottles kits for the ESSENTIALS, as a backup in case you get questionable readings on your strips, like a sudden, unexplained jump or decline in a parameter that's usually stable.
I just wish they made strips to test for CO2, Iron, and Phosphates.