For me this is easy, The anime AIR MASTER
it has one of the worst ending's i have ever seen in an anime, on of the characters has breasts literally bigger then her head, and displayed in a really unappealing way while bouncing independent of each other, one of the most annoying character's in anime, ignoring the laws of physics and gravity, and having a female as the main fighter (this is a tick on the list because most fighting heroines in anime are designated to fan service and being completely unrealistic. I.e. Long flowing hair then never gets messy or pulled in a fight, small frame with disproportionate power and speed, lack of muscle tone, they never sweat, and often have bullshit origins as to how they came to be fighters (ie they were trained by a master man martial artist dude bro perv happosai or a disciple of said thing)
The reason i like this anime is because the main character and fighter is actually believable. Shes well over 6' tall, was an Olympic athlete in a discipline that translates well into martial arts, has parents who are also champions of something or another that can translate into street fighting, and a lot of the combat is realistic (to an extent, if you ignore the ending). The characters, however annoying, have some charm and the love interest of the main character is big boobs character with bad voice acting.... I'm a sucker for love