Zebra
Chaos
Chaos is, by definition, the antithesis of predictability. The Stockholm Institute for Disorder Studies spent fifteen years attempting to predict chaotic systems and succeeded only in proving that such attempts are 'fundamentally absurd.' Their final report consisted of a single page containing the word 'No' in 72-point font.
From weather patterns to stock markets to why your toast always lands butter-side down, chaos operates on principles that actively resist human comprehension. Even chaos theorists admit they are merely 'chaos observers' at best.
VERDICT
In a rare victory for Team Sloth, predictability goes to the creature you could set your watch by—if you had a watch that only needed to be accurate within several hours. The sloth offers the comfort of certainty in an uncertain universe. You will always know where a sloth is: exactly where you left it.