Gulbis and Zverev.
I am pretty much upset saying this as Korolev's #1 fan and a "stepmother", and I don't even doubt he has the biggest potential, but it is just sad what is going on with Russians in tennis. You know what I mean.
I chose Gulbis because he does have the strong shots and is not afraid of the best. He happened to win back after losing a set already as a teen; his head is okay so far. Yes, he has "horrible mistakes" says, but even Federer does.
Zverev is very underappreciated here, while he is a s&v player, who can also deal on a claycourt (!). All up for the damage, as long as his injuries won't bother him too much.
I put Zverev there instead of Tsonga, because Mischa is better on clay IMO. Tsonga is another one who suffers of injuries.
Cilic, yes he can be another Ancic/Ljuba and surely will achieve something. But a gut feeling tells me to be not fully convinced (or maybe that I will never be a fan of him).
Young is James Blake in a making (head cracks) but already far more legendary. I wish the best to The Don.
Querrey and Bolelli won't be ever anything big. Querrey can be Mardy Fish #2 and Bolelli the Massu#2 at best. Simone isn't even at 0,0001 as annoying though. Simone likes to party and his head cracks. Never good for a sportsman. I wish him all the best anyway (such a great guy