Maria's vote for Kenzie showed just how sore a loser she was. And let's not forget, she's the one who turned on Charlie first. Charlie was just smart enough to side step it.
The reason I like Kenzie is she just seems like she made a real connection with everyone in the game. She may not have been the mastermind behind any crazy moves (I thought it was funny that Maria stole the Tiffany move right from under her), but she was rewarded for her social game. And her answer to Q's question about how she'd spend the money if she won, that was the thing that did it for her.
Like I said, I would have likely voted for Charlie, but Kenzie winning doesn't bother me at all.
I also agree with you about Ben's choice for the fire-making competition. If he was smart he would have chosen Charlie and Kenzie. I laughed when Liz was like, "fire is the one hole in my game!" What a delusional weirdo.