#1 Best Choice - Drew McIntyre
Other than the Miz, Drew McIntyre has been hurt the most from his dealings with Shane-O-Mac. The Scottish Psychopath lost to Roman Reigns at one PPV while Shane picked up a win over the Big Dog at Super ShowDown. McIntyre is too dang talented to be holding Shane's water. He should be drinking it and grabbing more drinks that lead to high-end accolades in WWE.
He was positioned as the top non-Brock Lesnar heel on RAW, but that partnership with McMahon has somewhat lessened his spot in WWE. He's still one of the most complete performers in the company but he needs a complete separation from Shane McMahon.
The best - and most sensible - way to do that would be a win in the King of the Ring Tournament. He's a heel and if a title shot is attached to winning the tournament, then it makes sense for him to win the tournament. Some recent reports have suggested that it's McIntyre who is the next challenger for Rollins, so a win in KOTR would back that up.
McIntyre desperately needs something that propels him into a consistent main-event presence and a Universal Championship win. Although Seth Rollins just won the belt back, the chances of him winning the title right away are slim.