I really don't know if any are actually quieter than others, I use Harbor Freight pumps because they are cheap. If you need it to be quieter, you could put a baffle in the tank or wrap the tank with some rubber foam. The rubber foam is used in pads like exercise mats. You can get some wire and wrap the tank with an exercise mat to keep the noise down.
As far as PH testers, I'm still using the cheap drops in a tube kit. It's working, but it sound like you want a constant read type, not a one time tester.
