Oooh. That's tough. Both are terrific choices, you can't really go wrong.
I tend to go for
Sarah Katherine, because
Anna and
Lilia together under one roof might get a little difficult. They don't share the same sounds, and it may just be me, but try calling "
Anna and
Lilia," as opposed to "
Anna,
Sarah!" It's just easier to distinguish the two. (Well, I had to use something to choose between them.)