I think this season had a lot of good seiyuu songs, more than usual.
It could be because there were two idol story anime, Love Live and
AKB0048, and they both have good songs.  Especially Love Live, which
has many songs as they use different insert songs in various episodes.
They probably just want to release a lot of CDs.

But among this season's songs, my favorite is "Girlish Lover",
the OP to Ore no Kanojo to Osananajimi ga Shuraba sugiru.
The song is sung by the four main seiyuu of this anime,
Tamura Yukari, Kayano Ai, Akasaki Chinatsu, Kanemoto Hisako.
Very catchy song.  Very cute voices.
Unfortunately they didn't release a CD single of this.
The only CD of it comes with the first DVD/bluray of the anime,
as an omake CD.

--
Hitoshi Doi
                         " this space for rent "
http://www.usagi.org/doi/                                    doi@usagi.org