PH testing equipment

So there are a lot of options concerning equipment. What brands work best?

I've been thinking of buying the multi-parameter water quality monitor from Stealthydro, but I'm unsure of the quality.
Link to this is http://www.stealthhydroponics.com/product.php?xProd=134&xSec=36

What do you guys recommend?

So apparently out of the 21 viewers no one has any recommendations on PH testing equipment.

sorry i viewed...i use drops and grow in coco