I don't know if anyone agrees with this, but choosing between Kenny and Jane was a fairly easy choice. If it was Kenny or Luke, now it would have been extremely more difficult!
I was Kenny's best friend back in season 1 and even though I still like him, his actions in season 2, albeit understandable, were not always easy to agree with. However, the guy is very protective over those he loves and I don't think he would hesitate to do what's gotta be done in order to protect Clem. Also, Kenny is reluctant about strangers as we have seen with Bonnie and the cabin group in S2 episode 2, so he wouldn't endanger Clem's life by welcoming a fucked-up person in their group.
Luke literally saved Clementine the moment he was introduced and did very little to be disliked. Having sex with Jane was a mistake, but he's still a good guy. We all saw his determination to save his whole group by following them to Carver's camp. He also risk his life to save AJ during the shootout if you don't do it yourself. Difficult not to trust him with your life honestly.
Now, if you take these two and compare them to Jane, why in the holy mother of Saltlick would you even go with her? I mean, what did she do for Clem?
Teached her a zombie-killing trick she already knew.
Proved her that she would leave a child behind to save her own skin.
Forced her to kill an old friend to prove a point (Determinant, but still).
Now to be fair, she did save Clem from the frozen lake, but that's like the only grateful thing I can recall from her.
With Kenny and Luke however, we both know they would do anything to save her and they would never abandon her. So why making us choose between Kenny and Jane, telltale?