Despite the two players' point totals being similar, I see them as having quite skillsets.
While Kerfoot gets offered around in proposals here all the time, but I actually think he's quite useful to the right team. He is OK defensively and can drive play with his speed and edge work, he's a decent playmaker too. Dvorak is a quiet type of player, he's decent defensively, good on Faceoffs, and a fairly solid playmaker too. He won't drive the play and needs good linemates to push the pace of the game. IMO he's been a little disappointing due to the price Montreal paid for him, but that's not his fault.
TLDR: Kerfoot can drive the play, Dvorak is the better center and at faceoffs, so it depends on what you want.
IMO- Dvorak's skillset is more valuable to both teams at the moment, so Toronto would have sweeten the pot.