#3 Goldberg
Ever since Roman Reigns and Goldberg went face to face, leading to a wonderful double spear to Braun Strowman, this has been a match that is just waiting to happen. Goldberg has not been seen since the Raw after WrestleMania 33, and he wasn't even featured on the show. He was in a post-Raw video, talking to the crowd and thanking them for his last run.
However, with Goldberg being the head of the Hall of Fame class this year, we could see him on Monday nights very soon. All that has to be done is have Goldberg come out claiming to be unstoppable, and have Reigns come out to interrupt him. Have maybe two more meetings on a Raw, followed up by a hard-hitting 5-10 match at WrestleMania, with Reigns getting the nod and having another legend's name under his belt.