#1 Sanity

Since their debut, Sanity has shown that they are a group to be feared. Whether it was their 'Purge' like attire or anarchic attitude, Sanity has proven during their time in NXT that challengers should quake in their boots.
Despite experiencing a change of personnel since their first appearance, they are no less of a force to be reckoned with. Many saw what Alexander Wolfe is capable of after he was an integral part of their NXT championship match against the Authors of Pain when they won the titles.
Although they are no longer champions, they are still a force regardless who their opposition happens to be. Their involvement in the tournament could lead to a number of potential finishes, one being that since they emerge the victors.
Sanity is definitely a threat to win the Classic and regains the popularity that made them as successful as they were as champions.