I voted for Golovin but it's very hard to say right now. They are all very good. It's very likely that the ones who seem more promising now, will have a letdown, and the others that are not so naturally talented will pass them coz they work harder.
Examples from the past - Kournikova, Lucic, Dokic, Stevenson, Henin, Myskina, Dementieva, Black, Krasnoroutskaya, Clijsters etc. Some peaked too soon, like reaching the SFs of a slam at a very young age(kournikova, stevenson, lucic, dementieva, dokic), while others took more time but caught up with them, and eventually passed them(Henin, Clijsters). And then there are others who were also junior no 1s, but had a tough time making their splash on tour (Black, and to a lesser extent, Krasnoroutskaya).
So I think it would be easier to ask "Who will get to the top15 or 10 faster", coz saying how their careers will be like at this stage, is very difficult
Threw my bad fortune
Off the top of
A tall building
I'd rather have done it with you
You don't have to hate your opponents to beat them - Kim Clijsters