I'd stay away from the Shapeoko. I don't have any experience with the millright CNC, but can recommend the Probotix Comet. I personally own their Meteor, as well as oversee another Meteor and Nebula where I work. I like their open frame (2 Y axis motors) design and linuxCNC which runs the machines.
They (Probotix) have recently updated their gantry design to a beefier beam, stiffer Z axis assembly, and taller risers so you can take advantage of the full 5" Z axis travel. A PC, monitor, keyboard,and mouse are included with linuxCNC already configured to run the machine.
You'll need software to create the toolpaths. Fusion 360 can be used, but I personally recommend VCarve Desktop as a far easier program to learn. They (vectric.com) have dozens of tutorials on their site to teach you the basics. You can download a free version to try out while watching the videos, although files you create won't cut until you've bought the retail version.