Need some opinions on which Stonecutters to purchase

If you think you daughter can get to 100 donuts then she'd surely be worthwhile getting Number 51 first (well, after the free skins) as that's a full character for just 10 donuts after the 90 donut rebate. Then she can start working her way through the rest of the skins. I wasn't playing during stonecutters so will get a couple of skins but I'm a sucker for new characters so will getting Number 51 first and then taking my chances in the mystery box for a new character as well.