Allow me to explain why you should vote for the Crabs. The claw can place and break blocks further away. This helps with building, PVP and overall useful even if it's just one or two blocks further.

The Armadillo's just give out dog armor which may be just be leather or iron. It won't improve the dog AI so it will still fall in lava etc.

The Penguins are just dolphins but with boats. Not the fastest way of traveling. So unless you're willing to move a lot of penguins to your nether ice way and assuming they don't have to be in water for it to work. It's just not going to work like you thought it would.