Must watch (right now!):
- Hajime no Ippo (insane music, good animation, hype, good story, including a movie and the best flashback ever in the latest season)
- Haikyuu (insanely good music and animation, very good story for a shounen manga, very likeable characters, many epic moment, sadly only 24 episodes right now, but second season is coming)
- Major (very very good baseball anime, season 1 is godlike each other season feels more like Rocky sequels, but are also very good - maybe hard to find?)
- Eyeshield 21 (Football anime which has many manly moments, animation is good, but the art could be way better like the manga. It still has a good story)
- Prince of Tennis (Well it's Tennis X Dragon Ball... not bad, but many filler episodes, although there are many OVAs, one movie and a sequel and more, characters are likeable, but shoujo bait)
- Yowamushi Pedal (Bicycle anime, but don't think that it's boring... Good characters, animation & art [good usage of 3D art), good soundtrack and two seasons - pacing is very good about 4-5 chapter/episode)
There are many more sports anime and I surely forgot some that I also like, but these are the ones which I remember sadly way too good, because I would like to rewatch them. Watch the first 4 episodes of each of them and you will get a "feel".