Another very fussy, takes a lot to get me gripped person here. In fact I started my own what do I watch thread two months ago and I've only just found something...
Would definitely say if you haven't already watched Breaking Bad (Netflix) to do so...
Others I've been obsessed with:
The Handmaid's Tale (but seen you've already watched it).
Line of Duty (BBC iplayer)
Hannibal (Amazon) - I prefer to the films.. It is a bit lot gory, but it is very clever, the characters are so well written and Hugh Dancy is amazing in it.
The Vampire Diaries (Netflix) - A bit teenagery to begin, but I think it is very well-written. Very believable and attractive characters (saying a lot for vampires! 
). If you liked Buffy, you'll enjoy this.
Firefly (Disney+) - Another Joss Whedon series. A bit of an odd premise, futuristic cowboys type environment, but as with Buffy, the setting almost becomes irrelevant. Great characters and script. Only one series sadly, but sort of concludes with a film, 'Serenity'.
And what I just started last night, but has immediately sucked me in: The Americans (but Disney+) which is about two Russian spies living undercover as an American couple in America during the Cold War.