Salifert is fairly consistent and easy to use, been using it forever at this point.
Red Sea are good as well, but their calculation is somewhat cumbersome to my taste.
Many recommend Aqua Forest as well as Tropic Marine, but I never tried them before.
I did switch to using Hanna Phosphate ULR in the last year or so, regular tests for PO4 are just too vague and have low resolution compared to colorimeters, although I was still able to manage without one for quite a long time.
I also installed GHL KH Director recently, it doesn't replace my weekly tests of kh with Salifert though, it's just there to alert me if an emergency test needs to be done and any decisions I made will be based on it rather than the automated result.