Everyone is going to have a least favorite genre of anime, but it was pretty surprising to me that it would be sports of things from this post I saw on r/anime.
Now, I'm not a big fan of sports anime, not a fan of sports in general. However, when it comes to the genre, there are some great anime with a focus on sports and the relationships built from being so competitive. Plus there are quite a few genres mixed together that aren't just sports, and could be appealing to a wider audience than just sport fans.
Regardless, I do want point out some great sport anime, and even a manga, that probably haven't got that many viewers because of it being in the genre of sports.
My favorite one on this list is Chihayafuru, there is a second season airing this season and it is just as good as the first. Chihayafuru isn't based on a "ball sport", it is more of a competitive card game, called hyakunin isshu or karuta.
Chihayafuru is one of the good examples of what you can do with a sports anime. It has memorable character that develop more as they get better at the game of karuta. Also, despite having never heard of karuta before watching Chihayafuru, the sport was explained well and demonstrated how exciting, yet beautiful, a competitive match was.
One other things that is more in the background, compared to the heavy focus on karuta, is the romantic aspect. It is subtle enough not to notice often, if you don't like that kind of stuff, but gives you small reminder that it is there, and might actually get its time to shine soon enough.
On the other end of the perspective we have Softenni, which isn't that serious of a sport anime, since it is a comedy as well. Looking at ratings online, it doesn't seem to be good, but I enjoyed it for what it was, a comedy with decent amount of focus on its sport.
Based on the title, you can tell what the sport is, soft tennis. With a health amount of comedy and a dash of sexual scenes, I would say Softenni was a pretty decent anime to look at; it also could be a nice introduction into sport anime, for people who haven't watched one.
The only manga, or manhwa since it is Korean, on this list is Girls of the Wild's. It is technically a martial arts manga, but its still a sport since they hold competitions at the school.
Girls of the Wild's is another mix of romance and sport, but it really isn't that focused on romance beside the first few volumes. Regardless, the fights are drawn beautifully and are exciting, especially when Song Jae Gu get into his first fight after training hard for it.
Victory
There was another anime that I personally haven't watched yet, but I've heard some good things about, Kuroko no Basket. Besides that, I hope more people will give sport anime a shot and similar polls, will have less people listing it as their least favorite anime genre.