I like Sakara at -138
I feel this fight will play out on the feet, where sakara will be technically superior. He's faster, hits harder, and throws a wider range of effective strikes with better mechanics.
I've seen Sakara fall apart and lose fights that he should have won, but i feel he is a little more disciplined recently.
Rivera is almost 10 years older, and quite frankly, i believe he is on his way out.