Honestly, it's all just a matter of perspective. There are plenty of people who prefer Twilight, and plenty who prefer Harry Potter, that doesn't mean that either series is genuinely better than the other, it just means people have different tastes.

Nope. 20-60 people is hardly representative of the entire population.
Plus, opinion polls never determine facts.
PLUS, in order for a poll to be worth anything, you'd have to randomly select participants, you can't have a selection of 100 Harry Potter fans and 5 Twilight fans, and expect honest results.

I know theres some people loves Harry Potter but some people loves Twilight...
And i think Twilight isnt the best and Harry Potter isnt too....
If u ask why the reason i picked 'yes' , its just an opinion...
Because, as u know, i prefer Harry Potter cause im a real fan of Daniel Radcliffe....
honestly, they had their own opinion about Harry Potter and Twilight....
U know, everyone has different opinion...

It concludes that more people like Harry Potter than Twilight on this website.

Polls are opinion based therefore you cannot expect some kind of definite result. There are millions of people that love Harry Potter, and there are millions of people that love Twilight. Obviously, not all of them are on this website, voting on these polls.
And there shouldn't be any official conclusion that one is better than the other because the two shouldn't really be compared. They're nothing alike.

It's based on one's opinion

Popularity is not a good reason.

Well, to me.
Besides if I want a real/genuine review about which one is better I won't choose fanpop.

It simply shows how many people are willing to part take in a poll.