Like any other manufacturing processes, there are pluses and minuses to each. The newer waterjet technology (OMAX tilt-a-jet or A-Jet for example) has very little clean up from taper. But with thicker material (several inches thick), the velocity does slow down and can create issues.
The laser has just as much issues with clean up, as the material gets thicker. But more importantly you have to consider material properties. A laser creates a heat effect zone which could cause serious strength issues, and also difficulty machining later.
For aluminum 1/4" Plate, waterjet is the way to go.
I was reading this and just wanted to toss my opinion in as for I am a laser programmer and operator. I run Mazak 8 kilowatt fiber optic lasers and cut aluminum with shop air or nitrogen and the speed at which it cuts soft metal like aluminum there is almost no heat. I can cut a part open the door and pick it up with my bare hands and it’s almost hard to feel any heat at all. Im probably a little bias given lasers have been my profession for almost 20 years but the lasers of today cut at a blinding speed with incredible precision without sacrificing the strength of the material. Well just wanted to add my opinion and love reading on here what people are always working on it’s really cool.