Neither lock, if you want that you need locking pliers/Mole grips/Vice grips depending on whether you want the generic term or the commonly used brand names.
I've looked at the Knipex ones and they're nice but expensive. The ones I played with also needed you to push the adjustment button in to change sizes. I've bought a pair of Irwin Vice Grip waterpump pliers and they're well built, nice to use and you only need to use the adjustment button to open out the pivot. To make the jaws smaller they just slide up on a sort of ratchet which makes adjustment quick.
I've had mine for nearly a year now and they're holding up really well despite being used on things far bigger than they really should have been used on. My boss liked them enough to buy a bigger set to replace a heap of crap water pump pliers we've had. The general consensus is they're a big improvement
Good tools are good