There are a lot of factors that make Batman's rogues gallery the most famous in all of comics.
There's the variety, for one, as Batman's enemies include everything from street level gangsters like Penguin, to international terrorists like Bane, to actual literal monsters like Killer Croc.
There's how the most famous of these villains thematically reflect Bruce Wayne as a character and the many ways he can go down the wrong path, like how Ra's al Ghul is a dark mirror to how Bruce wants to use his resources to change the world for the better, or how The Joker reflects Bruce's many mental health issues and whether or not being Batman is a help or hindrance to his trauma.
And of course, perhaps one of the most important factors: like Batman, they are all examples of how Gotham City just screws people over.
The real reason people love these villains so much is how you can plainly see that they are just people in pain. That's why Batman takes them to Arkham instead of prison, because he wants to actually HELP them. And these are by far the saddest and most tragic people to call Batman their enemy.
10. Man Bat
Addiction is a terrible enough thing here in the real world, one can only imagine how much it must suck in the DC universe, where you have to worry about getting hooked on a drug that turns you into a giant bat monster.
Enter Dr. Robert Langstrom, The Man Bat.
Like a lot of folks you'll see on this list, Dr. Langstrom started off as an actually pretty nice guy, all things considered. While his reasons for developing the Man Bat serum vary from source to source, originally he just wanted to be a superhero like the mysterious Batman. So, being a zoologist that focused on the study of bats, he decided to see if he could implement the biological advantages of a bat's biology onto human DNA.
Technically speaking, he succeeded. Kinda. Maybe. From a... certain point of view?
While Robert got the flight, speed, stamina, and echolocation abilities of a bat, he also adopted the animal instincts and temperament of one as well, making him a giant bat with the strength of a man.
So Batman defeats him and all's well, right? Not exactly. You can't just do that to yourself and walk away, so now Robert is hopelessly addicted to the serum. While he has put his abilities to heroic use like he'd originally wanted, such as his recent work with the Justice League Dark, his struggle with his inner animal is unfortunately one that he'll likely be fighting the rest of his life.