They already signed
Daniel Bryan (Bryan Danielson)
Sin Cara (Mistico)
Alberto Del Rio (Dos Caras Jr)
Evan Bourne (Matt Sydal)
Seth Rollins (Tyler Black)
Antonio Cesaro (Claudio Castagnoli)
Kassius Ohno (Chris Hero)
Dean Ambrose (Jon Moxley)
Tyson Kidd (TJ Wilson)
Yoshi Tatsu (Naofumi Yamamoto)
Lord Tensai (Giant Bernard)
Xavier Woods (Consequences Creed)
And they also had Kaval (Low-Ki) and Scotty Goldman (Colt Cabana) under contract before letting them go.
Me personally, I think they should bring Cabana back provided he gets to keep the Colt Cabana name. He's much much better than Zack Ryder and can put on a great match at that too. Kaval should have never been fired and yes, he was fired. He said so on the Art of Wrestling podcast that WWE told him to say he quit because it was better for everyone. Probably because they were afraid it would backfire like Bryan's original release if word got out and then they would have to rehire him. If they brought him back as a heel and had him do some matches with Rey Mysterio and Sin Cara, that would be amazing. But he probably won't give up his job in NJPW to come to WWE again.
Right now, I think the only big names that would fit in WWE are
Prince Devitt - Great wrestler. He would really fit in WWE in my opinion. He's Irish too.
Davey Richards - Probably the biggest ROH star right now. I don't want any arguments about his wrestling skill. WWE had him under a Developmental contract before, so clearly he's not completely off their radar.
Takeshi Morishima - He had a tryout match in 2009 and I can't for the life of me figure out why WWE didn't sign him. He's a great wrestler and could be the new Vader, only Japanese. WWE need a credible Japanese star anyway.
KENTA - Would probably never get signed due to CM Punk copying all his moves. But I'd love to see it either way.
Roderick Strong - Would be a good addition to the roster.
What do you think.