Categorize best Anime OST's

Ghost in the Shell and Death Note would probably be on my top. I would consider both mostly atmospheric.
Can't say I have a set favourite for best fight or sad music.

Best Fight/Hype Music: Hajime no Ippo
The guitar in the OST gets me pumped up everytime!
Best Sad/Emotional Music: Toradora!
If you've seen the show you know exactly which music I'm talking about.
Best Chill Music: Mushishi
You could easily fall into a trance with the OST. Great for falling asleep.

Every now and then I will do a full listen of the entire Madoka Magica Rebellion soundtrack. There are 45 tracks that are exclusive to the Rebellion movie and they are all amazing. Wonderful pieces of music ranging from soft and gentle to hard and energetic while keeping that eerie vibe throughout. I could be wrong on this but I believe the tracks are listed in order as they happened in the movie too so you sorta get this feeling of beginning to end listening to the whole thing.

Here it is on Youtube although I strongly recommend downloading a 320kbps version to get the best quality.

Best fight music: Naruto franchise, Fairy Tail, and Akame Ga Kill
Best soothing music: Nurarihyon no Mago and Buso Renkin
Best emotional music: Clannad franchise
Best all of the above music: K franchise

If you're looking for mostly acoustic/classical OSTs (the kind I prefer) I would recommend:

• Kiniro Mosaic and Gochuumon wa Usagi desu ka? OSTs (and Ruka Kawada's work in general)
• Yojouhan Shinwa Taikei OST
• Girls und Panzer OST

A little niche to be fair.

Most emotional(sad or chill, just fitting to any mood) OST: Owari no Seraph & Devilamn Crybaby
Best battle OSt: Owari no Seraph & Attack on titan

Your lie in April
Violet Evergarden
Yuru Camp
Tsuki ga Kirei