Doesn't have to be in your squad. 
 
For some reason I find Thane the most interesting. Always have him in my squad.

Zaeed, he has the best stories.

legion

I really like Jacob.
 
Interestingly enough, I also like Kanye West.

Mordin wins for me. I like all the new characters though.

Wait, I forgot about Mordin! Never mind Jacob, Mordy Mord's my favorite.

Legion was fascinating, but more for the information he provided than his character specifically, if you can even call him a "character."
 
So Mordin, basically.

1. Mordin
2. Thane
3. Jack
   

Thane was easily the most interesting. It's a pity that I had no real use for him.

Legion, or Miranda for the LI factor.

Grunt, I found his progress as a krogan intriguing 

Mordin, Thane, Samara and Grunt.

Grunt and Thane by far.

Legion and Thane and Mordin and Grunt and Samara and Miranda.

It's easier to ask me which one I don't like: Jacob

" It's easier to ask me which one I don't like: Jacob "

I think either Legion or Zaeed is my fave pair, can't seem to split the tie there. Legion is funny, Zaeed even when he's not gonna speak about anything but his little museum, he is pretty funny.
 
And legion knows how to dance. Infact, if only we picked up Legion first...he could have taught Grunt how to dance and we could have taken both to Omega while Grunt grows up through his adolescence stage.
 
 

1. Jacob/Grunt
2. Miranda

I like Miranda when I'm playing as my Fem-Shep. She's just good in battle and it's really easy to piss her off!

I like Miranda and Thane.

1. Legion
2. Mordin
3. Thane
4. Grunt.

Favorite new character is definitely Mordin. He's so well fleshed out and the conversations you have with him regarding his past work are great! He doesn't bullshit around, he tells you he's done some horrible things and made decisions that he wishes he didnt have to make but no one else could be trusted with. He regrets his past but he knows that what he did was necessary to help not just the galaxy as a whole, but also the group that he hurt with his work.
 
Honestly though, I loved all of the characters except for Jacob, and even he was pretty good, just so cut and dry compared to the rest of the cast. Huge nod to BioWare for putting the best cast of characters I remember saving the world with in a videogame.

Thane 
Grunt 
Mordin

Jack.  She compliments my adept fem-Shep quite well.

Mordin

Thane
Mordin
Jack
Legion

legion

Mordin, Legion, Samara, and Thane are my favorites of the new characters. I also like Grunt a lot more than I honestly expected from the pre-release coverage. The only new characters I didn't really like were Jack and Zaeed.

I love Thane's voice, his spirituality and role but really I can't stand his appearance close up.

" I think either Legion or Zaeed is my fave pair, can't seem to split the tie there. Legion is funny, Zaeed even when he's not gonna speak about anything but his little museum, he is pretty funny.
 
And legion knows how to dance. Infact, if only we picked up Legion first...he could have taught Grunt how to dance and we could have taken both to Omega while Grunt grows up through his adolescence stage.
 
 

"

Mordin because he's not only smart but actually does have a heart and genuinely cares about the unnecessary loss of life.
Legion because, hey, GETH SQUADMATE.

Thane

Thane is amazing.

The Illusive Man.

Thane.

Wow, a lot of Thane love. I didn't really find him all that awesome. He's alright I think.
 
Mordin is my favorite. Miranda is my least favorite.

The Illusive Man, because he's goddamn Martin Sheen. 
 

Thane came in way too late in the (my) game for me to grow attached to him. Same with Legion.

Has to be Jack, just cos the way you pick her up is soooooo cool! When she popped up out of that prison thingy, I was like, no way it's a girl! lol I loved that mission, I also really like Miranda, just cos she's got a nice ass :) 

I find Legion and Thane to be very interesting characters, I was thoroughly impressed they managed to make even the Geth show facial emotions.

1. Legion
2. Jack
3. Mordin

You know, I just realized why I never can figure out what about Jacob and Miranda it is that makes me feel like they're not as interesting as the other new characters. i played ME: Galaxy, so they weren't really new. All the other new squad members are great, though Samara is a bit bland. Legion and Mordin are best for pure interest, and EDI is pretty great. Again, TIM was't really new, since I read Ascension. Thane is a great character, and I like what they did with Grunt. The game is just damn amazing.

Thane always had something interesting to say.  I like the concept of Morinth but they short changed her on dialog.  A lot of people say Zaheed got the short end of the stick, but Morinth is way worse compared to him.

Legion!

" Thane was easily the most interesting. It's a pity that I had no real use for him. "

Samara and Legion.
 
Edit: Cant believe the lack of Samara love! She is so interesting!