I'd rank Julius above Nappie, and not just because he reads better; but Napoleon was best of his era, of that I wasn't in doubt before reading about this study. OTOH, I might rank Pompey the Great above Caesar, even though Caesar ultimately defeated Pompey -- both however added plenty of territory to the Roman Empire, and both were treated like dirt by the corrupt, lying jackasses of the Roman Senate.
The trouble with Caesar is that the only record we have of his Gaelic campaigns are Caesar’s own commentaries, which are generally considered to be very self serving. You can’t deny, though, that he did ultimately prevail. Much the same with his civil war commentaries. I still put him in the top 5 based on his results, but I would need some contemporary, third party corroboration of his battles to put him at number 1.