pH meter. I run my pH at the "upper end" 7.6-7.9. I cannot for the life of me tell the color differences. pH meter is simple. I fill the little cap and turn on the pH meter and run the FC test while the pH reading stabilizes.
I will also vote for the Speedstir. I thought it was a "joke" until I had one. Makes the tests so much easier. But to get the most out of it, get a few extra cylinders and a few extra magnetic pills.
Sample Sizer. Again, after having this I can't imagine not using it. Pour in water into tube, shove in sample sizer and remove. Perfect sample for repeatable testing.
Do you "NEED" these? No, but they make testing very quick and simple.
EDIT: On the pH meter, I bought the Apera AI209 PH20 meter from Amazon. I cannot rate the one sold at TFTESTKITS