When looking for specific styles of songs for different genres, there are many different ones that do wonderful arrangements.
Take for example orchestral music, and Tutti Sound comes to mind.
Eurobeat and A-One is one of the top around.
Halozy, 556mm parabellum, zytokine and east new sound for electronic
Undead corporation, crow's claw, iron attack and ui-70 for hard rock and metal.
Pizuya cell and unlucky morpheus for rock
Felt does great arrangements with vocals as well
Tamusic has a mix of classical and rock
And many hardcore hardstyle dubstep groups do wonderful creative takes of touhou songs, like Rolling Contact, Hardcore Tano*C, kusemono records, C.H.S. and spacelectro.
Vocals are also too wide and diverse to just pick a few, they all suit different styles of songs and it's not really fair to judge them with each other, seeing how they do different kinds of songs well. Like comparing a denpa singer with a rock one.
In short, it's hard to pick a best when the variety is too much, and they are not very comparable to each other.