@And Brother I Hurt People  
I think the answer to that is obvious.

Excellent points by my compatriots for Rarity. But you also said that out of all the Mane 6, she demonstrates her element least. Well let’s think about that. How many times does Applejack really get to display honesty. Not many. What about Rainbow Dash and loyalty? Also not many. Pinkie Pie and laughter? Okay, plenty, I’ll give you that one. Fluttershy and kindness? She’s too busy being scared of her own shadow! Twilight and magic? She’s a unicorn for crying out loud.
 
So, I mean really, aren’t you kind of nitpicking here?

@bboifatz
 
And even then, there is that incident with the Hydra.

You call selfish:
 
Offering her help to Applejack? (S2E1)  
Showing early concern for Twilight? (S2E3)  
Covering herself in mud and participating in something she hates for her sister? (S2E5)  
Considering Twi’s birthday almost as important as a chance to improve business and social status, and jeopardizing both to defend her friends? (S2E9)  
Making dresses for her friends (again) and protecting a gem for its sentimental value above everything else? (S2E10)  
Trying to help Fluttershy to improve her assertiveness and defending her from Iron Will? (S2E19)  
Following Spike out of concern and defend him from the other dragons? (S2E21)  
Confronting Sweetie Belle so she wouldn’t follow a bad path to earn her Cutie Mark? (S2E23)  
Camping, even though she hates it, for her sister and comforting her when she was scared? (S3E6)  
Stepping up to make Cadance’s headdress? (S3E12)  
Every other time she has helped someone along with her friends?
 
Generosity isn’t just about giving material things, you can also give your time, your concern, or your own comfort for someone else. And Rarity does that a lot.

@Background Pony
 
Are you an idiot?

@Ironbrony7  
Fluttershy being a bitch in Putting Your Hoof Down
 
Rainbow Dash being selfish in Mysterious Mare Do Well (and plenty of other episodes)
 
Applejack trying to trick Spike instead of telling him that he’s annoying her in Spike At Your Service  
Pinkie going Pinkamena in Party of One
 
So basically that leaves Twilight Sparkle as the only one with an untarnished record, since as far as I can remember she never forgot that she can use magic to solve her problems.

@Ironbrony7  
Because, while the other ponies are constantly representing their elements, Rarity hardly represents her element at all.

Also, I think you can find at least one instance from each of the Mane 6 where they don’t exactly represent their respective elements well, even without Discord. And yet here you are, picking on poor Rarity. :(

Everypony and everyone has their faults. Rarity just so happens to like fabulous things that make her appear the opposite of her element. Unfortunate, but she battles against it, like she did in the Sisterhooves Social. Now please, why so much hate mongering?

@Ironbrony7  
I said that she was generous there, but since then she hasn’t been.

And anyway, you never addressed my previous point of her making the dresses in the first place.

A generous someone wouldn’t turn down a free dress that a friend had made for them. The five basically turned Rarity’s dresses down and told her to go make new ones.

@CreakyCreek  
But it was shown multiple times that those weren’t Pinkie’s motivations.  
And you still haven’t proven that Rarity is more generous than any other member of the mane 6.

@CreakyCreek  
didn’t face her fears

@Background Pony  
To use your own logic against you, Pinkie only gave that wig to Cranky to try to make him like her, completely selfish motivations, and she had as hard a time getting Cadence presentable as the other mares did making fools of themselves to a complete stranger who they didn’t bother making sure was the right pony, and anyway Fluttershy did face her fears, she stood there and kept begging Rainbow Dash to let her off the hook up until RD rammed anyway, and everyone was doing everything they could to distract the crystal ponies, including Rarity.

@bboifatz  
It was never stated that Rarity gave the wig to Cranky freely. It’s more likely that Pinkie bought the wig from Rarity, making her the generous one.  
You’re implying that doing a princesses’ hair is more generous than running yourself ragged trying to entertain another pony.  
And I don’t remember Rarity driving herself crazy trying to help the crystal empire. If anyone was generous that episode, it was Fluttershy, who went faced her fears in order to entertain the crystal ponies. That is generosity, not making a bunch of woven baskets.

The same way she nearly drove herself crazy by making dresses according to her friends’ wishes, even though she knew the dresses were horrible. And she took the blame for it too.
 
But hey, of course that’s not generosity, what are we talking about.

She made a wig for a stranger who had no friends in town (Cranky Doodle).
 
Granted Rarity hasn’t exactly been at her best in Season 3 (then again, this whole season was kind of “meh” for the most part), but she at least volunteered to help Cadance with her hair, and practically drove herself crazy just to help her and the Crystal Empire.

@Background Pony  
He’s just blinded by hatred….

I smell a troll.

@Background Pony  
Define generosity, please.

Yeah, the Rarity who went against her better judgement to appease her friends would never do this.
 
The Rarity that stood in the face of everything she ever wanted and chose her “uncivilized” friends would never do this.
 
The Rarity that subtlety acknowledged Spike’s feeling towards her because she knew what it meant to him would never do this.