What model of power supply do each of those systems come with? THAT probably ought to be the determining factor if your are going to throw your money at a prebuilt system.
What are the full system specs of each system? It's not only likely, but probable, that you can build a MUCH better system for the same price using higher quality, better performing parts, if you do it yourself. And it's not difficult. Pretty much anybody with a screwdriver and a half ounce of common sense can assemble a PC in a couple of hours.