Crate handles tend to be custom wood elements built right into the crate design. This allows for a stronger bond between handle & crate than would be possible with screw-mounted chest handles, as well as more positions for hands. Putting the tops of the handles at around 24" from the bottom of the crate might look a little low at first, but it's a good position for lifting.
I agree with Chris. My favorite type of handle is just the common wooden version that runs the width of the crate. As long as someone hits it with a round-over bit to knock off the corners and then make sure that they put in a few screws (I don't know how many times I have seen a handle pop off because someone just tacked it with a couple of of staples!) then it is hard to beat.
The metal ones are ok on travel frames I guess but they are not very comfortable if the painting is heavy. The cushioned ones are better but boy are they pricey.
Height is the most important thing with handles to me. Check with folks around you and measure the height from the floor to the palm of their hand while it is clenched in a fist and then subtract at least four inches so the crate can clear the instep while standing upright.
Also remember with painting crates someone may be lifting one end so someone else can put a dolly underneath it. You don't want that person to be lifting a heavy crate up to shoulder height if you can help it so even lower than that may be better.
Ashley makes some good points about wood handles that have been a standard. If the crate gets longer that 8 ft in length I like to run the wood handles along the length of the crate. This reinforces the lid and back and allows two or more people to lift from one end of the crate.