Showtime's was of course more athletically imressive.. but damn a fonr face kick to knock out a top challenger with really ur 1st strike of the night is mind blowing shit.. video game stuff.. both amazing.. but Silvas is the greatest kick in MMA history !
Showtimes kick ftw 
Silva's kick actually led to the end of the fight.
Silva > Pettis
Calhoon's Anderson hate is hilarious.
Pettis' was much flashier but Anderson's actually, you know, finished the fight. Against a guy who has never been KO'd in 14 years of fighting, no less.
I have to say the more "impressive" one would be the one that knocked a guy out, especially a top guy like Vitor. If you meant the "rarer" or cooler" one, then its open to debate.
the chief - Silva's kick actually led to the end of the fight.So did Pettis'.
Silva > Pettis
Pettis by a mile. Silva's was just a standard front kick, Pettis was something never seen before.
Calhoon - If you youtube both kicks you will see a ton of front kick ko's from a variety of styles and competitions including Karate, Kickboxing, Thai boxing, MMA, etc.
However there is only one Showtime kick.
Don't be such a fan boy that you blow up a front kick to be amazing just because it came from Anderson Silva. Instead ask yourself how you would react if Anderson were able to pull off a Showtime kick, in such amazing fasion in such a close fight, in the last round of the last W.E.C. event ever. I think the answer will be pretty clear to you then.
Showtime's kick was awesome and prolly a lil bit cooler, but not by much. you are a fool to downplay the greatness of Anderson's kick. You act as if its no big deal to finish an MMA fight with a front kick. That was one of the coolest moments in MMA history.
Showtime is a one of a kind kick. Silva's, as impressive as it was, isnt unique.
thats like asking to pick your fav child. in that case i pick silvas maybe because the occasion and the opponent edges it his way
Dude.
He jumped off the FUCKING CAGE.
Showtime kick was jaw-dropping, Silva's kick was brutal...
Showtime and it isn't close.
The Pettis kick was a lot more impressive. That said, Anderson is the most impressive fighter in the world.
The simplicity and devastating effectiveness of Silva's kick exemplifies martial arts. Pettis's kick was prettier but not as effective.
Silva's.
Chris Power - Dude.
He jumped off the FUCKING CAGE.
I have no idea how the kicks are even being compared. There is nothing special or unique about Silvas' kick. It is routine and it simply landed correctly.
Pettis jumped off the fucking cage and spinned around and kicked Henderson in the face and knocked him down.
Silva stood there and front kicked Belfort in the face and Belfort was KO'd.
This is not the first ever KO kick and will not be the last and I have no idea why there is such a big deal and discussion over it.
Silvas' kick was not special, we will be lucky to ever see a kick like Pettis' kick in MMA ever again.
PoWdA101 - I have no idea how the kicks are even being compared. There is nothing special or unique about Silvas' kick. It is routine and it simply landed correctly.
Pettis jumped off the fucking cage and spinned around and kicked Henderson in the face and knocked him down.
Silva stood there and front kicked Belfort in the face and Belfort was KO'd.
This is not the first ever KO kick and will not be the last and I have no idea why there is such a big deal and discussion over it.
Silvas' kick was not special, we will be lucky to ever see a kick like Pettis' kick in MMA ever again.
You are either a troll or a dumbass. probably both
not special! are you serious?
silva's kick has been used in the past in K-1, it's nothing new.
you may never see any fighter other than pettis to use the cage to land a kick.
brownchickenbrowncow - not special! are you serious?
You are an idiot.
Seriously, if you have ever trained a stand up martial art that mattered I would shit myself. You can't think Silvas' kick was special in any way. Sure it was Silva, sure he knocked Blefort out with it, does any of this make the kick "Special." FUCK NO.
I seriously learned a front kick on like my first or second day of Kickboxing class.
Seriously.
Just because it was a huge Main Event doesn't make the kick some kind of new thing. Belfort got kicked in the head, Belfort got KTFO.