Personality: Karin is by far the worst. Sakura and Hinata are both really nice and friendly but I'd say Sakura has the better personality because she's more outgoing and confident.
Strength: Sakura wins here
Accomplishments: Hinata has done stuff but nothing compared to the other two. Karin's accomplishments were healing her teammates/saving Sasuke, destroying the wooden statue to get to Sasuke and assisting Sasuke. I can't think of much else. Sakura has done the most for her village: killing a member of Akatusuki, healing hundreds of people before and after war, saving up enough chakra to use her strength of a hundred seal, punching a god, saving Naruto, Sasuke, Hinata, Kankuro etc.
Looks: I'd say it's a tie between Sakura and Hinata. Karin is pretty too but she always looks angry all the time so her looks suffer because of it.
So Sakura would be the best Konoichi and overall character.