All right, here we go. As I've already defended Pompey once above, I think I'll take a different approach here in the beginning. As for this Rustaham, the General who defeated Crassus in Parthia. Well...let's face it. Crassus was a nobody in terms of military matters. He was his own worst enemy. He didn't listen to the advice of his subordinates (including his own son, and many of whom were better commanders than he was). He trusted a native Arab who ended up leading him in the desert (against the wishes and advice of his subordinates). He also lost the trust of his soldiers by disregarding the omens of the gods. Sure, Rustaham did good to annihilate Crassus; but Crassus was by no means an able general, at least during this campaign.
On the other hand, there is Pompey. He held one triumph for each continent where he was victorious: Europe, Africa, and Asia. He defeat Albanians, Iberians, Armenians, Nubians, Jews, Romans, Spaniards, slaves, and rid the Med. Sea of pirates. Note, he did not celebrate triumphs for victories over the slaves or the pirates. The point of these two is that 1, in the case of the slaves, he cleaned up the mess left by Crassus, and 2, in the case of the pirates, he demonstrated his exceptional organizational skills. Furthermore, the Senate appointed him over the grain distribution, and he filled Rome's markets to the point of overflowing. Then, the Senate appointed him as sole consul during the end of Caesar's provincial command in Gaul to deter Caesar from marching on Rome. Even Cato, who was avidly against Pompey, voted for this. Finally, the only serious defeat Pompey ever suffered was against Rome's greatest general (arguably), and one of the greatest generals of all time. Napoleon studied his tactics; generals today still study his tactics. And, the only reason Pompey lost was because he was outwitted at the last second by Caesar.
I think the choice is very clear.