Wood strips (cleats) are much easier on the finger tips when carrying honey-laden supers and are all I use. That said, commercial beekeepers usually prefer the mortised hand holds because they allow you to stack the boxes tighter together when transporting.
The commercially available hand holds are usually done on a shaper with a large profile cutter. You can come close with a table saw by slowly raising the blade, then tilting it, then raising it more, then tilting it back etc until it "scorps" the mortise. You can also use a dado set, a router, an adze, etc. but the profile won't be quite the same.
