#1 Sami Zayn

The Underdog from the Underground is astonishingly without a single title reign on the main roster, despite spending over two years as one of the company's best workers.
His role as a heel has somewhat elevated him in terms entertainment, but unfortunately, it has not helped him secure a title so far. With 2018 halfway done, there is still hope for Zayn to win a belt this year.
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His brilliance in NXT has been undermined on SmackDown and Raw, as Zayn has struggled to impress the WWE management, despite being a fan-favorite all over the globe.
The Canadian's determination and his passion towards the business makes him the most worthwhile and deserving candidate to win a title at the topmost level, the sooner it happens, the better.
The WWE needs to act fast on Zayn since it won't be long before it gets to such a frustrating level that his work-rate and performances may drop. Zayn has often been close to a belt, but that's as far as he has gotten in the WWE.