Str, agi and sta. Roughly in that order.
Str is the most important for me, because it adds AP to both bear and cat forms, but I've read that you shouldn't do much for it when you have about 1k AP.
Sta is good for the obvious choice - you can't kill things, if you're dead.
Agi is great for cat form, because it adds AP (though half of what str adds), and because it increases your chance to dodge and crit. As said earlier, past 1k AP you would probably want to focus on agi, for a higher crit chance.
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I'm scissors. Paper's fine, Rock needs a nerf.