I tried to get the most popular shows in this pick. If some of them aren't, my bad. It's kinda hard to remember all in my head.
So if your choice is missing, feel free to add it :)

Anyways. I picked the Supernatural fans 'cause I've never seen any fans that are so dedicated to the show as they are. All the picks, quizzes and other contributions to the spot (For example the weekly interview with the fans!) show how much they all love this show and how much they really love it. As a Supernatural lover myself I know how much all the other fans love it. If you take a look at the picks on the spot you will find out how dedicated the fans are :P The picks always makes me think. Sometimes I'm like "Is there anything I didn't get in that episode?" 'cause of the detail questions :P

Buffy fans are also incredibly dedicated. The Scoobies Awards are evidence of that.
And House fans!
But I went with Supernatural because like kristine said- the fans really think about the show and come up with really detailed picks. Also, several of us created the Supernatural Viewing Party Spot, where we're watching the whole series over again as a group and discussing it episode by episode, making content for them etc. Everyone's been superdedicated to it! ;D

The words have been taken out of my mouth :)
I also think that we, Supernatural fans are super-dedicated :)

Sane people can not match us. Although, Supernatural fans are trying really hard.

We really love Lost. House fans and OTHfans are didicated so much too also GA fans

I completely agree with Kristine and fanfly.The things that the SPN fans come up with are completely detailed, sometimes I doubt even if the creator of the show has thought so much about certain elements of the show.Even when the fans are displeased with certain aspects of the show, they always express their opinion in a very civilised manner.
OTH and House fans are also really dedicated to their show.

lol Kristine, I knew this would be your pick LMAO but anyways, to me it seems that The OTH Fans are more dedicated to the show, because from my observations, they are dedicated to their favorite character and their favorite couple

We are still obsessing over a show that ended years ago...say no more:P

Same as Buffyfan92. Supernatural is still going hard, still fresh in people's minds, whereas Buffy ended back in 2003, and our spot is active and full of dedicated (and die-hard and fanatic) fans.
I actually went back and forth between the two spots to see which had more picks, videos, etc. It was pretty even. Buffy outweighed SPN with picks and quizzes by A LOT, whereas SPN beat Buffy with videos and links by A LOT. Buffy also had more forum topics, and SPN had about 8 more articles.
So if you choose based on spot activity, it's pretty much a tie. But if you look at the big picture- Buffy has the more dedicated fans.
Runners up include One Tree Hill, House M.D, Grey's Anatomy, Friends, Scrubs, and Lost (I've never actually watched any of those shows but the fans do show dedication, which I've noticed a lot).
Edited due to my mind has trouble spelling simple words such as "our", and switches it to "uor".

We're crazy mofos in that spot!

Next thing we'll come up with is a special robe to wear, and a special chant to recite before we think about it, watch it, or try to make a pick.

Don't mess with us, our fandom is strong!

But jokes aside, I've never seen a spot that has more love, more friendship and dedication pouring out of it. It's like the fans there have learned from the Winchester bond and developed something similar, many other fandoms are at war over territory and politics... we're Utopia... at least in Fanpop :D

No doubt!!! we're just crazy like that!!!

Defo House Fans Lol. But Gossip Girl, One Tree Hil And Supernatural Fans Could Give Them A Run For There Money Lol.

house,gossip girl,lost...at least i am

well put it this way 4+ one tree hill fans got banned on fanpop for standing up for something they believed in. others are refusing to come on here anymore. i think that screams dedicated tbh. i love you guys <3 :')

the oth spot sucks without my guys <3 but still everybodys dedicated on there.

I watch all of these shows bar Sex and the City and i've gotta say while One Tree Hill fans are pretty dedicated as with Supernatural fans the House MD fans are out of this world!

Duhhhhhhhhhhh.

Bones 4 ever!!!!

were the bestest

Lost, SPN, GG, Sex and the City, Skins and BtVS fans are all dedicated fans although I don't like GG.

I think the word is "obsessive"! XD

Dedicated enough to keep watching, lol.

Nobody can come near 2 buffy
Hello it finished almost 10 years ago and have you seen how many fans it still has!!!!!!

Well... I heard Dean Winchester is the queen of tumblr!

Besides I am dedicated enough to vote for me as most dedicated fan xD