Delpo reaching the first spot is a much more difficult task than Murray getting a Slam.
Therefore odds are Murray will do it first.
besides, Delpo has an obstacle called grass if he wants the first spot. I'm confident he will get to QF and maybe SF this year at Wimbledon.
Muzza has 2 obstacles - grass and clay.
Also a third one - he is limited to defense only and there will always be at least one in form player in the slams to take him out at one point.
Muzza needs to change dramatically to have chances for a slam tittle and honetly i can't see him doing that in the next 3-4 years.
On the other side Del Pony can win a couple of them this year and jump on top of ATP faster than one would expect.
My vote goes for Pony #1, even though i'm no fan of his, but he's the face of the new generation of champs.
Muzza should be happy to reach the semies anywhere