This was a brief video review of four DIY Security systems that do not use cameras. It looks like the target audience was apartment renters who find security cameras creepy. The only use case considered was an intrusion alert, they didn’t get into the issue of smoke detectors at all.
The four selected as worthy of mention were interesting: nest secure, ring protect, simplisafe, and smartthings/ADT. The review was just for the base kit, essentially one motion sensor pointed at the front door and a couple of contact sensors on the windows.
I would tend to agree with their conclusions, for what that’s worth. 
Ring: easy to set up and use, and ended up being the top choice if you didn’t need other home automation features, but in the separate podcast they mentioned that individual devices felt cheap and it wasn’t clear if the long term quality was there. But at half the price of the other systems, this was their first choice.
Nest: Aesthetically the most pleasing, easy to use and set up, they liked the key fob and the ability to identify different family members, but still seemed expensive for what you got.
Simplisafe: easy to use and set up, professional monitoring was a good option, seems like a solid security company.
SmartThings/ADT: The most powerful with the most integrations with other smart home devices, but also the most complicated to use. Seemed like an odd amalgam of old and new tech. (The panel, in particular, was called out as seeming like something from an older system.) although it cost more than the other systems, it clearly offered many more features including leak sensors.
As I mentioned, they didn’t go into other use case details in the video, but I’ll go ahead and note that even though nest makes the nest protect smoke detectors, they cannot be tied into the security system, and ring doesn’t have smoke detectors at all.
Both simplisafe and ADT/SmartThings have add on on smoke detectors which can be added to the professional monitoring if desired. 
