I'm gonna say Broadchurch. I don't think it was unpopular, but I have to look it up every time to remember the name. It features a past and future Doctor (as in, Dr Who). David Tennant was a Doctor before he was on Broadchurch, and Jodie Whittaker was a Doctor after. She plays a mum whose child goes missing, and he's the inspector sent to her remote (?) village to investigate. That's the first season. The second season deals with the town's issues with the bad guy from the first season, and I forget what the third season's about, but it's all good.

They made an American one, and some of the same people were in it, but it only lasted one season. So I'd say go with the British one.

I also appreciated Torchwood. It's an adult sci-fi series set in the Dr Who universe, and it had its ups and downs (mostly downs), but it was generally worth watching. Unfortunately, the lead actor had a bad habit of pulling his pecker out backstage to prank his coworkers and he got canceled for it. Nobody said he ever abused them or that he pulled it out in public, it was just schoolboy antics backstage, but it was enough. Not defending him, I'm just saying he's not a nonce or a public menace. He just has a problem with boundaries. So, while I don't dislike him as an actor, being a viewer, I fully understand why people don't want to work with him anymore. Torchwood has continued as audiobooks, I think, or maybe something like a podcast where they act out roles? They call it something else, like an audio drama or something. So I'm not sure if there are actual books they're reading from or just a script that isn't available in print, the audio recordings being the only medium. There were also a couple games as I recall, but nothing good. A less problematic and more straightforward series (albeit, American) is Warehouse 13. Same thing. Shadowy organisation collects alien relics and stores them for the government. Hijinks ensue. W13 was fun at first, but really didn't go anywhere. (Also, it was on Syfy, if that tells you anything — as in, the network couldn't be arsed to spell "sci-fi" properly and they cared about as much about how to make good sci-fi as they did about spelling it properly.)