What do you do when you have a bunch of opinions? How do you evaluate them?
Anyway, my answer is a simple $30 Hanna from ebay. Ph does not have to be measured that closely for what we do. And no, you don't need calibration solutions (RO or distilled water is 7.0) and you don't need to calibrate to 4 just 7. Some meters don't even allow you to calibrate to 4. Spend the money on something that will count like better nutes or better seeds.