#1 Seth Rollins

Seth Rollins is the man in WWE right now but presumably his contract is up for renewal currently, much like his former Shield buddy, Dean Ambrose.
Unlike Ambrose, WWE have largely done right by Rollins as a singles guy. He received the big push after the initial Shield split back in 2014, won the WWE Championship from Brock Lesnar, at Wrestlemania 31 no less, and held onto the strap for most of the year.
Even after he returned to the mid-card after his lukewarm match with Triple H at Wrestlemania 33, he was a featured part of television. His consistently excellent matches earned him the respect and support of the WWE Universe, which has taken him to a Royal Rumble victory and potential title win over Lesnar once again at Wrestlemania 35.
He would be a good fit in AEW, with his youth, athleticism and star power, and people still recall his Ring of Honor run as Tyler Black. However, WWE has given him the keys to the kingdom. Why would he leave?