There were people who swore by Splitfire spark plugs, too. Fuel line magnets, you name it. No matter how gimicky the product you'll always be able to find people who absolutely swear by the improvements that they've had that are solely attributable to said gimick.
So, as guitar333 said, everybody has their opinions. Asking which of something is "best" depends on what people mean by "best". Best how? Cost? Bling-Bling value? Performance? What does "performance" mean for this particular tidbit?
So it's not surprising that no matter the topic there are a variety of opinions, as many folks have different things in mind when they say "best".
All you can do is try to find as much info as possible and decide for yourself. The topics you mention have been discussed here many times and there are also information sources on other sites.
