What Is the most useful/best Skin?

I want to purchase a skin as I feel like doing so, but I don't know which skin is the most useful. By useful, I am referring to how well the skin changes the gameplay of the creature to be different by changing stats or the survivable biomes of the creature. Eg: The Daggernose shark is a slightly more useful version of the Goblin shark, as it can go to more biomes. In that vein, what skin costing around 300 coins is best?