Just put a monitor in your dash - that way everyone can see it.
But if you insist on headrests, let someone else with experience answer your "what is better" question, but...
If you need replacement headrests, the best place to go is to your neighborhood junkyard. Look for a U WRENCH IT, or a Pick-n-pull... anything that lets you in with whatever tools you want to pull whatever you want.
Ex.: A lady hit my door and damaged only the door... so I got a $1600 check from the insurance company to get it professionally fixed... then i went to the U WRENCH IT in my area and picked up a new door that looked pretty decent for about $45.
Brian