What is the difference besides plugs? Is one better than the other in hash rate or reliability that people have noticed?
good luck 
So you are saying Other Computer Cables & Connectors for Sale - eBay this, version 7 would be the best to get for stability and reliability?
My personal preference is to avoid the SATA connector types as it has less capacity to deliver as much wattage as the other types. Of the ones listed I would go with the version 006C as it has a 6-pin PCIe connector plus additional voltage regulation. The second choice would be the 4-pin Molex types.
As far as quality, I think with any of them with ver003 and above circuit boards are ok as long as you avoid the sata power connector types. I have some earlier ver001 and ver002 boards with really bad solder joints and would avoid them. The rest are a mix of ver003, 004, 005, and 006C and they all perform equally well.
The only issue I have had is sometimes the USB3 cable they include is junk, you may need to order higher quality USB3 ones. I also use slightly longer USB cables for some of the cards as the included ones are too short for adequate GPU spacing if you start trying to go with 5, 6 or 7 GPU rigs.
Do you have a preferred USB3 cable?