My three-year-old son loves wrestling. His favorite is Shinsuke Nakamura right now. Nakamura wears red, red is his favorite color, it works.
We sat on the aisle at a NXT house show and Nakamura touched fingertips with my son, who starts crying from the happiness like it's BeatleMania. He really dislikes the guys Nakamura feuds with (every time he sees his Samoa Joe figure, he cuts a promo about Joe pushing Nakamura down on NXT TV).
He also likes Sin Cara, Bayley, Cena, New Day, Sami Zayn, Jack Gallagher, and No Way Jose, and is very specifically into Royal Rumble matches. He was super into Kalisto when he first started watching, but it seems to have died down.