This is the one I purchased, from Amazon called Cheerlink Konnwei KW902, however it was from the vendor Auto Car, but now it is from Cather Store which I have never dealt with,:https://www.amazon.com/gp/product/B00Q5YRC4C/ref=od_aui_detailpages00?ie=UTF8&psc=1
I liked this specific model because it was recommended on the forum here, and also it has an on/off switch, which I used for awhile but now leave it on all the time, so far without problems. I stopped using the switch because I started worrying that it might not be high enough quality to do a huge number of on/off cycles, and at $19.99 I didn't want a little $0.02 switch causing a problem.
I also purchased from Amazon a "Y cable connector" male to dual female Konnwei cable from the vendor YeeOBD for $8.90, but unfortunately it looks like it isn't in stock now:https://www.amazon.com/gp/product/B012BZN96S/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
I would say, at a minimum, you must get a cable extender so that you can plug in to the LEAF OBD2 port, and never touch again, and then plug your OBD2 piece into the cable. Without a "Y cable" though, you will have to remove the OBD2 piece each time you take the car to the dealer, with my "Y cable" I've just left everything and they've plugged into the other connector. They have never commented about the setup either, which I followed from somebody else, possibly in the previous thread mentioned, where they got a long enough cable to reach the center console.
I have been happy with the quality of the Konnwei products, but the Nissan LEAF OBD2 connector is incredibly fragile in my opinion, so you must be extremely careful doing the initial plugin.