Disney animators went around their office building and asked all of the women the most attractive things they found in men and created Flynn based on those physical/personality characteristics.
That is why Flynn is now being called the most attractive male character that Disney has ever created.
Flynn is also rumored to be modeled after Ezio Auditore da Firenze from Assassin's Creed series.
Flynn is also extremely similar to Aladdin.
They both are believed to be orphans.(For Aladdin only in the first and second movie)
They both are thieves at the beginning of the movie
They are both first seen running away from the law.
They both have a captain of the guard who tries to capture or execute them (Flynn it was the Captain of the Guard, for Aladdin it was Razoul.
When they are both about to be executed, they are saved by a former enemy turned friend. (Aladdin was saved by Iago. (Iago broke the glass ball that was holding Genie) and Flynn was saved by Maximus. (Maximus went and got the Pub thugs to help Flynn escape and Maximus took him to Rapunzel)
They both are the only Disney Princes to be paupers and marry a princess
They both are arrested and thrown in jail , due to the involvment of the main antagonist.(Gothel for Flynn, Jafar for Aladdin)
They both come close to being executed (Flynn by hanging, Aladdin by decapitation)
They both go by assume names at one point.
They both get married to a princess of royal blood in a sequel film.
They both are able to win the trust and blessing of their love interest's parents, despite a criminal past.
They both become allies with a character that was originally an enemy.(Maximus for Flynn, Iago for Aladdin)
They both foreshadow a royal life in the beginning of the film. (Flynn announces he would like a palace just like the one in Corona, Aladdin tells Abu everything will be different and one day they will be rich, live in a palace, and never have to worry.)
They both rescue their interest from forced servitude from the main antagonist.
Flynn is noted as a funny character.
Just some interesting stuff I found about Flynn for all those Tangled fans! :)