And I'm not saying Slendy is better than Jeff, or Jeff is better than Slendy, that's your opinnion. I personally like Slenderman better because he is the monster that got me into Creepypasta so I love him a lot.
If Kaline were Jeff:
Kaline: Slendyyy! Give it back!
Kaline: *Jumps and tries to get it*
Slender: *Hold it higher*
Kaline: -_- *Kicks him in the nuts*
Slender: *Drops the knife*
Kaline: Yay! *Takes the knife and runs off*