I am not sure about this .. but I think both of them !

That's a tough question, I may even change my answer.. :/

both? i was gonna say vanessa because she slept with chuck but than i remembered that georgina also did lol

is really hard to answer this...

but the difference that vanessa slept with chuck while blair was in love with him unlike georgina she slept with him just as a bitch and chuck and blair were just friends that time not even close a lover !!

I think that she dislike Georgina more because she messed up Serena`s life a lot, she was Chuck`s first and now she is trying to sabotage her by being her roomate in NYU. She doesn`t like Vanessa either but mostly because she lives in Brooklin and recently because she slept with Chuck. She didn`t seem to give it a lot of thought though considering that she had slept with Jack too so...

I don`t know, she pretty much hates them both. I might change my answer later too.

idk....maybe

i think that in season 1 she definitely disliked georgina more because of what she did to serena. but then vanessa slept with chuck and they never liked each other anyways. but i think that blair doesn't care so much for vanessa because in her eyes vanessa is just the girl from brooklynn who slept with chuck.
but georgina can be very manipulative and you can never be sure what she will do next so blair knows that she shouldn't underestimate the danger that comes with georgina. and imo they won't become friends in college but let's see what happens.

This was REALLY,I mean REALLY tough as long as I don't like both of them...

clearly she hates more geogina.
i mean Vanessa for Blair is like someone she looks down on, who's not worth her time.
But with georgina is bitch against bitch haha, it's actual hate.

Yeah, I agree with solsis. I'm pretty sure Blair hates Georgina WAY more than she hates Vanessa... For Vanessa, she doesn't even think of her enough to hate her. She's shown much more hatred towards Georgina, who is actually a bitch and they are sworn, official enemies.

I think both of those sluts,but maybe Georgina more!!!!!!!!!!!!!!!!!!!
I don't like both of them,so In season 1 she had all the right to hate Georgina,because of her cruelty to Serena and because she was Chuck's first and she is trying to make Blair unable to communicate in college!!
Georgina is just awful homewrecking whore!!!
Hopefully she isn't long with Blair!

i think she dislikes Vanessa more. Even in a episode the freshman she said to G, and i quote 'I know your out to get me, because you started an allience with Vanessa the one person that i may hate even more than you.'

Vanessa,but i think she dislike both.

'I know your out to get me, because you started an allience with Vanessa the one person that i may hate even more than you.'

Exactly! Plus V slept with her man. So did G, but you know what I mean.