Welcome to the forum kxc223!
For an objective comparison of the various options, go here:
Sorting through the opinions will take much longer. In short, here are a couple of my thoughts on the current state of affairs:
The 430n RHB is a Garmin-based unit that has shipped on many of the WK2s. Some folks prefer the Garmin interface. Some (like me) were not crazy about it at first but have come to enjoy it. There is a software update in development that was due in January but has been delayed. It is supposed to address a variety of issues with broken features, and is supposed to enable Sirius Travel Link feature. However, I saw a comment here recently that suggested that the RHB's hardware is not compatible with the TL feature. I think we're still waiting for some clarity on this issue. Chrysler is supposed to be mailing an update disk to owners with this unit.
The 730n RER has shipped in many units and is a Harman-based unit. Some prefer the less "cartoony" maps and other features in this nav system. A software update was recently released that reportedly fixed an issue with iPhone connectivity. The RER comes with a little pigtail iPhone/iPad connector in the cubby in the center stack (vs the center console arm rest USB port in vehicles with the 430n RHB). From all accounts this is a perfectly adequate navi system and media center.
The 730n RHR is phantomware to date. While you can read about its purported features in the link above, no one has seen one yet.
My .02: I was originally in the group of folks willing to wait for the RHR. I then found an Overland on a dealer lot that was available. It had the Adaptive Cruise Control which I had not originally ordered, but it had the 430n. It has turned out to be an excellent decision to purchase this setup and I have no complaints nor do I feel like I compromised on the navi. Good luck researching the options and enjoy the forum. Great group of Jeep fans here!