Though I do love both.

Most definitely. Nightwish is basically all I love about music wrapped up into one band. I like variety - Nightwish has covered at least nine genres throughout their career, and they've included at least nine more elements within those genres, some of which are my absolute favorites. I love opera-trained sopranos, versatility, and soothing lower registers in female singers, and I love classically trained vocals, death growls, and raspy vocals in male singers - what do you know, Nightwish has used all of those at some point throughout their career. I am very picky with songwriting because I like poetic lyrics about fantasy, dark subjects, and love (if done correctly!) and Nightwish has far exceeded my expectations - 'Open thy veins for my venom, kiss the cobras with thy twisted tongue. So shalt thou join the emryrean circus where beggars mourn and seraphs dance. In this twilight cathedral, shall I wed thee O bride of the netherworld' and Would you do it with me, heal the scars and change the stars? Would you do it for me, turn loose the heaven within? I'd take you away, castaway on a lonely day. Bosom for a teary cheek, my song can but borrow your grace are just a few examples. Good musicianship with several members of the band is also a plus.

It's not that I have anything against Flyleaf - in fact, being religious myself I quite admire their lyrics for what they are - but the band's vocals and overall sound don't really interest me.

It was hard to pick though.

I love Nightwish and am not familiar with Flyleaf. But I know of a fair amount of people with a similar taste to me who like them, so I'll have to check them out someday. ^^