Among the best superhero films ever created is 1978's Superman. This movie has an escapist factor similar to that of Star Wars (Episode IV - A New Hope) from 1977.
The film starts on the planet Krypton, where a red star is about to wipe out the entire planet. Jor-El (Marlon Brando) warns the Kryptonians about this, but they refuse to believe him. Jor-El decides to send his only child, Kal-El, away to Earth to give him a chance in life. Jor-El delivers a powerful speech to his son, and yes, he was reading his lines, but that doesn't hurt anything. Yes, it's lazy, but that's what made Brando unique because he was the only one who could do that.
On Earth, Kal-El is adopted by Jonathan Kent (Glenn Ford) and Martha Kent (Phyllis Thaxter) and given the name "Clark Kent." We later cut to Clark's teenage years, where he is played by Jeff East, though his voice is dubbed over by Christopher Reeve. He loses Pa Kent after receiving a life lesson: despite all his powers, he can't save everyone. Once he turns 18, he has to leave home and go north to discover the Fortress of Solitude. He finds a crystal that contains a part of Jor-El's soul. Superman makes that his new home, both as Superman and as Clark Kent, in the city of Metropolis. Clark Kent starts his new life as a superhero and as a journalist. Adult Clark Kent is played by Christopher Reeve, who not only played Superman, but he IS Superman.
The film also stars Gene Hackman as Lex Luthor, the main villain, and Margot Kidder as Lois Lane, Superman's love interest. The love story between Superman and Lois is what makes Superman a great picture. Despite the 4-5 year age gap between the two actors, they have incredible chemistry and make the love story work.
What also makes Superman great is how thrilling, enjoyable, tidy, and lively it is. The casting, John Williams' score, special effects (especially the flying effects), set design, and morals all work exceptionally well. This film is also very pretty to look at and that's thanks to the late Geoffrey Unsworth, who was the film's cinematographer. Before Superman, Geoffrey Unsworth was the cinematorapher of Stanley Kubrick's 2001: A Space Odessey (2001).
These days, the film might be seen as cheesy, but I think lighthearted superhero films are the least concerning aspect. What I look for in a superhero movie are the plot, the characters, and their development. That's why I like Christopher Nolan's Dark Knight Trilogy, Sam Raimi's Spider-Man Trilogy, and the X-Men films, such as X-Men (2000), X2: X-Men United (2003), X-Men: First Class (2011), and X-Men: Days of Future Past (2014).
But going back to Superman: as I said, Christopher Reeve not only played Superman, he IS Superman, and forever, Christopher Reeve will be Superman. And no, I don't think Brando's portrayal of Jor-El was lazy. Brando was just different, and even Richard Donner said he liked Brando's performance.