Connor may have been an integral part of the plot of Ats but he is not really a likeable character. Yes, a lot of the show would have to be rewritten without him but the point is, it should have been rewritten.
Kennedy is the one who wants to fight the demons, unlike the rest of the potentials.
She is the one who distracts Willow with a kiss and in two seconds, the pall of Tara's death is lifted.
She is the one who stays with Willow even when she morphs into Warren.
She is the one who agrees to act as bait for the bringers.
She is the one who leads basic training.
She is the only potential I would want to bring to a fight if I had to fight.
In terms of most people, she is the one who started from a position of wealth and would have had more to lose than the rest but she was the most effective fighter.