I use Bendix (Php700-900/pr depending on size).

If you are using the original alloy wheels, take off the wheel and peer into the brake caliper (the chunky thing that's riding on the round brake rotor)


There will usually be a viewing window (opening) on the caliper to help you see:


When the pad wears down, the brake indicator starts contacting the brake rotor and it makes a high pitched sound (braking is still not affected early on). But its time to have the brakes checked before its too late:


New brake pads look really thick (this is the brand I usually use on units when we replace pads):