IHMO they are like Apples and Oranges. In 9mm, both will be more affordable to shoot...
I think if you want an accurate, sturdy, AR "style" ambidextrous non-restricted black rifle, with quad rails, custom options, and apparently great customer service, check out the JR.
If you want a compact LIGHT backpack plinker, with potentially iffy sights, but a fun little unit for plinking, camping, or maybe security use, check out the Sub 2k.
I like both a lot, for entirely different reasons. At the range, people generally wanted to know exactly what the JR is (more than a few times), and think the Sub 2000 is a pellet gun and not a real firearm.