Another Disney Channel alumni, Sabrina Carpenter, played Maya on Girl Meets World before moving into a singing career, including opening for Taylor Swift. Thus, she's a good package of blonde hair, a good actress, and a great singing voice for the role. Carpenter can bring more attitude to Rapunzel and shine nicely and already has experience with Disney. She might not be the traditional princess, but Carpenter could handle the role nicely.
Anyone who can survive seven seasons on the CW's crazy Riverdale can handle a big-budget Disney movie. Lili Reinhart's turn as Betty on the show went from wide-eyed innocent to vixen while indulging in nice songs. Even toned down, Reinhart can capture Rapunzel being the outside, locked in a tower all her life, and the wild antics when she escapes. With Riverdale finished, Reinhart as Rapunzel would be a huge boost for her career and provide a good edge for the role.