Honestly, there aren't any full songs on this album that really make me think "I would be so sad if this song didn't exist." I think it's because every song sounds like something she's done (better?) before. Microphone is like every other rock song she's done, count down is like a very lackluster version of her other mid-tempo rock tracks, Don't look back is like a darker version of vogue, Sexy little things and Sunrise are anything on NEXT LEVEL, You were... is a typical winter ballad, RED LINE ~for TA~ was done with MY ALL (though I DO like RED LINE better), BALLAD is not her first oriental ballad and not her most exciting one either. I'm not trying to say that her works now are "unoriginal" and that I want her to do something new and exciting. I don't mind if her works sound like her previous works, as long as they're nearly as good as them. I think these songs just fall flat when you compare them to their earlier counterparts.
My favorite song on the album, Last Links, still has really poor production imo. Kind of sad considering it's my favorite and all. :| Though if I have to pick a song to answer the 2nd question, "Which songs you would just cry if you heard clips of them or heard the full thing one time but could never listen to them again", it would be Last Links. I would be pretty sad if I weren't able to hear the full song after the amazing preview it had. (I've experienced this before with my favorite band too. There was a 1:40ish preview of the most amazing song EVER, but then the single release was canceled due to a scandal and now I'll never hear the song in full. It does make me really sad.

)
Anyways, this is just my opinion, so I'm sorry if it offends certain people who can't handle any negative criticism of Ayu's works.