In Persona 3? I rather liked Akihiko, myself. I'm slightly biased because I romanced him with my FeMC, but still. I liked his character, and he way more level-headed than Junpei. I'm sorry Fynn - we won't see eye to eye on this one!
I also really liked Shinji, and it is a great shame we don't get to see more of him in the team. I actually rather disliked him at first, as he came across as really anti-social and broody, but his experiences with the team made me warm to him. Also, he gets fantastic development in Persona Q, which made me fall in love with the character.
Ken is okay. Mr. Carny really hates Ken, but I didn't mind him. And Koromaru is very sweet, but I honestly can't justify calling him my favourite.