I'll be different and go with #4
I'm going to assume you'll leave these in all the time for the added "cool" factor. (cool)
Hooks are good, (solid over hollow) but there is alway a chance you could throw the strap off.
D ring is great, and the gadget factor gives extra points on the cool meter... but you have to mess with opening it up to use it. Get a few years of muck in the threads of the pin and it gets stuck. Oh yeah, there can be some rattling of the D ring as you drive. Any reciever will "clunk" around some, but you now have two items to "clunk" around.
With the ring, just remove it, thread your tow strap through, slide the looped end over the square tube, and insert it back into the hitch, no way your strap is coming off, no messing with hooks, threaded pins, clips, etc... It's as easy as the strap into the reciever trick.