Caesar for me is just a much more exciting, romantic sort of figure. It's why he had the love of the people and why he's been such a compelling figure for over 2000 years. It's why Shakespeare wrote a play about him and why to this day there are movies about him. Octavian was a more cold, ruthless sort of operator. Caesar was at the forefront of Rome's cultural revolution. He dressed with flair and was Rome's most fashionable man decades before he became anything in politics or in the army; he set every fashion trend that was being copied ten years down the track by others like P. Clodius Pulcher. He slept around freely, and threw the city's hottest parties. He was that kind of guy whom all the cool crowd liked. He made being against the Senate and for the people cool just because that's what he was about and everyone wanted to dress like him, walk like him, fukk around like him, party like him, and hell even do politics like him. Caesar's charisma must have been so powerful, one only need look at the time he spent with the pirates who captured him as a young man and how he befriended them all, and also look at the fierce and unending loyalty of all the soldiers he commanded.
Octavian on the other hand was a rigid moralistic conservative, totally divorced from the radical counter-culture Caesar helped create. Look at how he treated poets like Ovid who lived a Caesarian lifestyle and wrote about it too. And look also at the laws he passed which were all about restoring the outdated traditional Roman morality that people had been paying lip service to since basically the end of the Second Punic War almost two centuries previously. Nobody likes a boring conservative wet blanket ass killjoy, hence Octavian just doesn't compare to Caesar as far as public acclaim and lasting impact on popular culture do. Who wants to watch a movie or play about Octavian?
A comparison between them is like comparing Avon (Caesar) to Marlo (Octavian) from The Wire. One ends up in jail/assassinated and the other walks free/dies naturally. But who was the greater man? Avon, no question