Since I know I'll be playing the game for years I'd most likely convert that chicken into a golden chicken just so if I do win that means 10% bonus DEC from the win. Over time that can really add up.
Like your kraken I might go Oaken Behmoth. While they are non effective in low battles they pack an almost insta win fully leveled on a high mana battle. Depending on the cost between them would depend on what one I would try and max first. You also need some little guys for the front lines and well yeah now I'm over $500 most likely ðŸ˜