Like to listen to? If so, I completely suggest "Cassis" and "Reila". Other good ones are "Chizuru", "Red", "Taion" and "Regret". But generally, all the songs are great to listen to ^^
Taion, Cassis, Reila, Pledge, Headache Man, Guren, Invisible Wall, Art Drawn por Vomit, Before I Decay, Zakurogata no Yuutsu, True Murderous Intent, Zetsu, SHIVER, Silly God Disco, Voiceless Fear, and Filth in the Beauty, there are so many más but I'm just lazy.