He's average in the ring, but has superb mic skills and loads of charisma.
I only hate his character.
Absolutely. His character (how he's booked and the promos he does) is what's hurting him. He's not worse in the ring than many others who don't draw hate like he does. But the whole Cena character is just unbearable.
Re: If Cena was good in the ring would you like him?
Cena's performance in the ring is absolutely ok, it's the character the people don't like.
Or said in another way: People don't like how Cena is booked. If Cena turns heel, Cena-Haters will love him, I am sure!