Aokiji took one look at Ohara and changed forever into lazy justice, while he was doing this, what was his goal? To become Fleet Admiral, the position of total control over the Navy. He sucked it up, took his promotions and aimed for the top, showing only passion for the FA position. Once he couldn't attain that, he quit immediately without a second thought.
Garp is a fraud forever. This dude witnessed a genocide and even Imu, yet stayed put with no aspirations for change. He's a bonafide bootlicker.