Not sure if there really is an all-in-one smart home security system. In my opinion a lot of them are lacking in some way or another.

It also depends on how you define security system. I wouldn't say cameras alone are a security system. If you're looking for a more casual way to get notified or monitor, these new "smart" solutions are great. If you're looking for a true "depend on it for your life" security system, you might end up feeling they come up short.

But Simpli-Safe is one option that comes close. It has a hub with siren, keypad, door/window sensors, indoor cameras, motion sensors, backup cell service, and available professional monitoring. It does not have outdoor cameras, however. And it does not do typical smart home tasks.

Samsung SmartThings is a very capable smart home hub that can interface with all sorts of devices -- lights, locks, cameras, sirens, motion sensors, contact sensors, temperature sensors, thermostats, etc. It also has a built in security app called "Smart Home Monitor" that you create rules for. Personally this is what I use, as it doesn't require a monthly fee and can still alert me remotely when things happen, as well as do things like turn on lights and sound a siren when an intrusion has been detected. Optionally, you can have it professionally monitored by Scout Alarm, but that is something I don't feel the need for. Biggest downside is it is dependent on having an internet connection. It is very configurable with some 3rd party tools. It takes some technical know how and comfort with computers, though, but if you're a tech geek it by far offers the most options. You don't have to deep dive with SmartThings, but you may find some of the out of the box security features lacking, and if you just want a set it and forget it approach, Simpli-Safe is probably better.

SmartThings also offers an ADT branded smart hub that lets you use ADT's sensors and professional monitoring service, but lets you control it via a touch screen that can also do things like turn on and off lights, control thermostats, etc.

Because SmartThings is a fairly open third party system, you could integrate other supported camera products into that ecosystem like Ring Video Doorbell, or the wireless Arlo Pro security cameras, as well.

Another well-rounded choice from Google is the Nest line of devices. They offer advanced indoor and outdoor cameras, a great thermostat, smoke and CO alarm, and forthcoming video doorbell and security system including the option for professional monitoring. On the pricer end but in my experience their products are not only stylish, but work well.