The Rockwell Model T will beat the Parker hands down, mainly because of good quality control and superior materials. But the Parker will cost less, which is something.
Depends on how well Parker does with the quality control on these. Apart from that from what I can tell they're going to be copies of razors from different time periods, the Parker is copying the early adjustables and the Rockwell looks like a copy of a Super Adjustable or a Slim.
I'm just glad that new adjustables (especially TTO adjustables) are being made, these are complicated machines that aren't cheap to make and if multiple companies think the market is strong enough to support that risk it's a good thing.