None really. They all have a large fan-base.

& Tina.

def. emma.

Rachel, really?

tina/Mercedes, maybe Mike and I guess Emma.

and LOL at Rachel winning this pick

Rachel?, you are kidding me right?, she's hardly underappriciated in any way, everyone seems to love her (aside from me and a few other people) and she's most definitely not underappriciated on the show, same for Blaine who has the same amount of votes as Mercedes!, *sigh*, i'm sorry but this fandom is just ridiculous sometimes.

Um come on people... Rachel wins all the picks for favorite characters, doesn't sound unappreciated to me.

I can't believe that Rachel's actually winning this. It's UNDER APPRECIATED not OVER APPRECIATED

Emma doesn't get HALF the love she deserves.

Mercedes, Tina, Mike AND Emma, who the heck chose Rachel. She's always first choice for 8 out of 10 of the songs in Glee Club and just because Finn is being stupid right now doesn't mean she's under appreciated i totally agree with The-man, it's ppl who are UNDER APPRECIATED not OVER APPRECIATED, and Rachel as much as i'm warming up to her, is way over appreciated, it's like ppl don't realize there are ppl there other than Quinn, Blaine, Kurt, Finn, Rachel and Puck. And Klaine aren't under appreciated, they are getting much love nowadays.

I just think emma dosent get half the credit she deserves

Rachel?? lol

Like everyone else is stating, why the hell would Rachel be the most under-appreciated character ? Come on, read the question properly, for God's sake, and stop picking her because she's your favorite character.
I picked Tina because I think she's kinda been neglected by the writers, pretty much since the beginning, but I could also have chosen Mike, or Mercedes, or Emma. Those 4 are by far the most under-appreciated characters, though I don't know why because they're pretty awesome as well, as much as the other characters. And Blaine, really ? He's been there since 2x06 and somehow managed to get more screen-time than Puck. It's not that I don't like him, or Rachel, not at all, it's just that it doesn't seem fair to me =/

Whoever said Rachel, a whole lot of people are liking her. Tina and Emma are clearly underappreciated if you hadn't noticed. They hardly get as many solos are Rachel does, and all the ones Tina gets are either screwed up or made into a better version (ex. "Tonight", "I Kissed A Girl", etc.). Emma is sweet, too. How could someone not appreciate her character?

Tina and Emma should be the top 2, in my thoughts. Rachel...no way.