why do yonko fans like Garp more than Akainu serious question
Think it's because Yonkou fans like the characters because of their hype/wank, as Yonkou don't share many other similarities with each other (completely different designs, fighting styles, personalities etc.). Admirals are more grounded in this regard, they simply have a job to do and are following orders. There isn't this rebellious free air around them, and the wank that comes with it naturally.
Garp embodies that free air, and the wank that comes with it. He's linked to the MC. It's the portrayal over substance type of character, similar to Shanks. A lot of talk, not a lot of action. Admirals are complete opposite of this, where they are all action and receive very little wank/help from Oda. They speak through their feats, not through links to the MC and intangible hype.
Garp's assessment falls more in line with the Yonkou than the the rest of the marines. It's why majority of marine haters are drawn to him.