I would love to see CxptainGrayson (https://twitter.com/Cxptaingrayson) be invited to Zenkai! Not only does she make all her own cosplays and edits photos, but she also streams her progress on Twitch and has guested at several conventions over the years!
I would have to suggest to all time favorites, Johnny Yong Bosch and Yuri Lowenthal. Bosch has done many great voices of the past and present including the all time classic Akira movie. Lowenthal has been a recent legend that voices for many antagonists including Sasuke from Naruto and Jinno/Kuma from Afro Samurai. Another honorable mention would be Christopher Sabat, Vegeta/Piccolo of DBZ or more recently My Hero Academia.