User blog comment:CykeP/And Now I'm Torn/@comment-26341692-20151101102628

I say Dex and Daina, since they should be easier, but you can buy Rin/Len too, although I don't know how they'll sound, and if they'll have that annoying accent that Miku has too.

Just buy whoever fits you, but I say go for the DD's. ^^