I think Ikuta Toma's Ore no Hanashi wa Nagai will be hot in Japan this autumn as The blue sky suggested. I'll probably watch that one. But I am most looking forward to you-and-i-on-the-g-string though.
But if I only had time for one and only one Jdrama, I think that I'd choose something that had completed airing and had generally good reviews. For a busy person it is the worst to give several hours to a drama and realize that it just isn't for you. Maybe something like juhan-shuttai or nigeru-wa-haji-da-ga-yaku-ni-tatsu which are both from 2016?