Well, I guess we cannot decide this for you neither am I able to choose one as my top candidate, but I'll give you my opinion.
As for nummber 1, I don't know. I refreshed it several times, but it wouldn't play.
Number 2: Although it's a bit variated with more cello in the background, I think "Requiem for a dream" is just a little bit overused. It pairs up with "Pirates of the Carribean" which I both hear at least twice at a competition.
Number 3: Not my cup of tea. I'm a big fan of Kylas gymnastics and she interprets it rather well but I still don't like vocals that much. I'd say this is a piece for gymnasts with long, elegant lines and if it fits you and you want to hear it all season, go ahead!
Number 4: A piece for the power gymnasts, if your gymnastics relies on tumbling this is your music.
Number 5: Germanys best Junior gymnast uses this music and she's stunning to watch. If you can dance plus get a feeling for the music (which in my opinion Jessica Lopez missed a bit) this is a real crowd pleaser.
Number 6: I also love this one, certainly because it would fit me as a gymnast, but I agree with Kiwi, if you are an expresive dancer this might get you everyones attention.
Take your time to think about it and what type of gymnast you are, try to just dance a bit to all of the pieces and you will quickly know with which you feel most comfortable.