Audition song good enough or not?

I have a singing audition coming up for the x-factor and I'm thinking of the song 'Aint no mountain high enough - Marvin Gaye' I have been told I'm fairly good at singing it but just wondering if that isn't too old and do they want new songs? I'm 17 years old 18 soon and I'm a girl. I want an opinion on my song choice or any suggestions would be greatly appreciated. Anything from Alicia Keys to Kelly Clarkson. Thanks!