Belle definitely. she was the only one who loved the beast, treated him kindly and never cared for his looks. she made him see the bright side of the world. he loved her so much that he didn't care whether he will change back into a human or not of she wasn't happy.
I think it's a tie between Belle and Ariel. Beast loved Belle so much that he let her go so she could save her dad. He totally sacrificed love and his only chance to become human again. That's deep love. Also Ariel is adored by Eric. He fell in love with her not with love at first sight, but sound at first hearing. It didn't matter if she was a mermaid either. He jumped into that sea knowing he had to fight a sea witch because he loved a "fish". There love is just so sweet to me.
