There area lot of parameters by which you could determine a top, all-time military commander.
-For winning set piece battles and season long campaigns: Suvarov, Agrippa or Napoleon
-For holding an army together on a shoestring for nine years with all the odds stacked against you and always outnumbered (And not being a great tactical planner): George Washington
-For a fast, hard hitting attack and exploiting weaknesses: Erwin Rommel
-For a devastating, relentless pursuit to wipe out a retreating enemy: George Patton
-For astounding success building a two million man Army from 20,000 regulars in 18 months, with new equipment, on the other side of planet, and fighting your allies as much as the enemy, all while under intense personal stress: John J. Pershing
-For both planning and waging a relentless, successful campaign which literally shortened a major war: William Sherman
-For managing to hold together an army which was 1/3 in mutiny, while your nation was out of reserves and running out of everything you needed to fight and the enemy was literally a few days from your capitol: Ferdinand Foch
-For long term campaigns full of victorious battles: Hannibal
-For winning battle after battle, outnumbered, with all of Europe against you and being blind: Jan Zizka
-For repeated successful delaying actions, avoiding disadvantageous battle and shadowing a superior enemy who was a legendary General and patience to strike only at the precise advantageous moment- Fabius (Quintus Fabius Maximus Verrucosu)