From our experience with Phantom's plates, laser cut is more precise, as the laser beam is a lot smaller than water jet's water beam. At least for the 2 shops we used. The first Phantom prototype plate was waterjet cut, and the inside corners are rounded. It was difficult to install switches, especially plate mount stabilizers, without filing off the corners. The actual shippng Phantom plates were cut with laser.
I would recommend using laser cut even if water jet is a lot cheaper. Sorry if this has already been covered earlier in the thread.