10 - 12 hours would be good enough imo!
10 hours is a little less that i would like to be honest. in games like these i really like it when it takes longer, because it makes me feel at the end that i went a far way from where i started, it helps with that sense of adventure. like in TLoU, it feels like you look back at the start and is like "yeah... i came a long way since that!"