They don't exist. It just takes too much time, money and is like capturing lightning in a bottle. So while you care more about presentation and less about the story, most have a good story but bad presentation.
The newest one that seems like it might be captivating is
Unsolved, but there's only 1 episode so jury is out. This our best bet for overall best package - story, narrative, presentation etc.
Otherwise there is
Missing Maura, which has wonderful source material but is basically like listening to 2 drunks rant about everything they've read in no particular order. It's just a mess. But it's worth reading an article or two about Maura, this event is interesting. Then there is
48 Hours - Hannah Graham, which is actually interesting but the narrator's voice is a turn off for a lot of people. This one is ok. Finally there's
Breakdown, which I can't remember anything about so I guess that says enough about how I feel about it, and if you can deal with the story being fake,
Limetown, which is 100% made up.
You're not going to find one as interesting as Serial. Sarah is great at creating a narrative, and others fail at that. I recommend
Unsolved, and then checking out Criminal.
Criminal is awesome, each episode stands a lone. A lot of the earlier episodes are better than the newer ones, so start at the beginning. Finally
Invisibilia is put together amazingly, I would check out the Batman episode. It's not about Batman, it's about blind people who can see, like bats.