Guderian might deserve to be there more than Rommell.
I would also try to find a way to fit Gustav Adolphus, the Swedish military commadner during the 30 years war.
Actually there are so many military geniuses over the course of history I'm just going to name my list.
1. Belisarius
2. Philip II/Alexander the Great/Parmenio (Their military fortunes are too intertwined and dependent on each other to be seperate.)
3. Genghis Khan
4. Scipius Africanus
5. Sherman, because IMHO his military and nonmilitary actions won the Civil War for the union
6. Themistocles
7. Gustav Adolphus
8. Napoleon
9. Timur-i-Lang
10. Babur
I tried to make a list that varied over a large span of time and distance but it is pretty ridiculous to attempt.
REFORMS IN THE LEGIONS
Now commander-in-chief of Rome's African legions, Marius came face to face with a problem that would eventually result in his greatest contribution to Roman legionary organization. From the very beginning of its history, Rome had accepted only soldiers of means, capable of purchasing their own armor and supplies and, as owners of land and property, having a financial stake in the success of Roman arms. Any Roman male who did not meet the property and land qualifications was not permitted to serve. The armies of the Republic had been almost continuously at war for the entire second century, from the Second Punic War to the wars against Jugurtha. Rome and her Italian allies had been systematically denuded of suitable manpower to fight for Rome's new, imperial, obligations. Marius, who probably had little real understanding of the earthshaking implications of his idea, decided to go for manpower to the despised capite censi, the "head count"; in other words, the illiterate, landless, volatile Roman mob. For generations, small farmers had been displaced in Italy as wealthy senators and knights bought up their land and put slaves to work it. Since the Gracchi, thousands of displaced former landholders had swelled the city of Rome. The landless had fought before in Rome's armies in minor, supportive positions. Marius proposed to give them all full-time employment.
Historians of Rome agree that this single action, which took poor men and put them under a great general who promised them booty, land upon retirement, and forged an emotional relationship with them, created a whole new type of soldier, loyal not to Rome's institutions, but to the status and wealth his general could provide. In addition, having no homes or land to go back to, the new soldiers tended to become career professionals, in the legions for 20-25 years before retirement. Marius' new legions prefigured Caesar's troops crossing the Rubicon, the later Praetorian Guard who made and broke Emperors, and the eventual empowerment of the Roman legions to choose and control the autocrats of state. All this, however, was buried in the future. At the moment, in 107 BC, Marius simply ignored the law requiring that Roman soldiers own anywhere from 3,000 to 11,000 sestertii in property, and filled his armies from the milling Roman mob.
In addition, he made the kind of pragmatic changes in organization and weaponry that shows his quality as a practical soldier. Marius altered the way that the pilum (the throwing spear of the common soldier) was fixed to the shaft; this caused the point to break off upon impact, which meant Rome's enemies could not return the spear against her legions. Marius altered baggage arrangements, insisting that his soldiers carry tents, weapons, and food upon their backs - hence the so-called "Marius' Mules" - rather than slow down the legions by endless baggage trains. Pliny stated that the earlier Republican army had five standards: eagle, wolf, Minotaur, horse, and boar. Marius elevated the Eagle - symbol of Jupiter Optimus Maximus - to the universal legionary standard, which fostered a subconscious loyalty and pride among the common soldiers. Most importantly, Marius is credited with switching from the maniple to the cohort as the core tactical element of the legion. The maniple had consisted of four various units of soldiers, each bearing different weapons, and thus used differently in combat. The cohort eliminated the more poorly equipped units of the maniple and, essentially, permitted the state to arm all legionaries with similar equipment. Rather than the complex subgroups of the maniple, the cohort functioned upon six identical units of 80 soldiers each, or 480 men to a cohort. Rather than forming in long lines, the cohorts combined in lines of three cohorts each, in depth, which permitted autonomy to each unit and flexibility in formation. Finally, Marius began promoting officers from within the ranks, rather than utilizing political or social connections, which vastly improved the quality of the centurions and other officers leading the legions on a day-to-day basis.