#2 Sheamus
It might come as a surprise to people, but Sheamus is one of the most successful Superstars in the history of WWE. Sheamus has won all the active championships in WWE except the Intercontinental championship and then newly formed Universal Championship. Apart from the championships, Sheamus has also won King of the Ring, Money in the Bank and the Royal Rumble.
The Celtic Warrior's work in the ring and his achievements are criminally underrated. However, his time at the top of the card seems to be over. Sheamus has enjoyed enormous success as a part of "The Bar" along with Cesaro since 2016. The duo has won the Raw Tag Team championships a record 4 times.
In 2017, Sheamus revealed that he was wrestling despite having stenosis in his neck. The Irishman's days in wrestling are limited and the most WWE can do with him is have him win the Intercontinental title.