It *may* be that the metal back of cartridge pad carriers transfers the brake arm pressure to the tips of the pads better. It *will* be that you can't actually perceive the difference, and so this doesn't matter.

I prefer the cartridges as they're quicker to renew - the only adjustment required for the thicker new pad should be at the cable barrel adjuster.

I think "squealiness" is as much related to hardness of the pad as anything. Cheap hard pads seem more prone.