I typed a huge response but seem to be having issues posting it, so hopefully this will work. . .
I am typically a "lurker," but I had to register so that I could respond to this thread. I just wanted to say that FB/Twitter/website/etc. poll results ARE indicative of the general consensus. I have a Bachelor's degree in Sociology (yes, I am much older than most iCarly fans but not afraid to admit that). When a Sociologist performs a study, he/she polls a "sample" of the population in question, given that it is typically not feasible to survey the entire population. When a sample is random and unbiased, one can draw conclusions about the entire population based on the results for the sample population. That being said, Seddie's popularity in internet polls is likely reflective of its popularity with iCarly fans who do not use the internet. Also, someone made the argument that online polls aren't reliable due to the fact that people can vote more than once, but that does not skew the results. If only Seddie fans could vote more than once, that would make sense; however, both Seddie AND Creddie fans are capable of voting more than once.
I am a Seddie shipper. I think that it has to do, at least partially, with the lack of chemistry between Nathan and Miranda. When they kiss in iSYL, I have to look away. Seriously. It feels like they're a pair of siblings attempting to make out. Nathan and Jennette, however, have tremendous chemistry between them, to the point that you can always feel the "heat" and tension between them, whether they're kissing, arguing, fighting or just standing next to one another. That's just my opinion, though.