Hi,
I have been installing smart devices from a few different brands. I am having issues with my Ring devices getting signal. I am considering buying more ring z-wave extenders, but I am wondering if I could buy a much more powerful Z-wave extender that is still compatible.
Are there brands that offer compatible z-wave extenders. I have had a tough time learning about this issue. Thanks!
Manufacturer doesn’t matter as long as your device conforms to the ZWave spec.
That said, most hardwired ZWave devices act as ZWave extenders. Most people just invest in either hardwired ZWave switches, pocket sockets or controlled outlets.
Personally I went the GE / Jasco hardwired switch route. Just replacing all of my switches in my home gives me nearly 35 wired ZWave plus repeaters.
Z wave extenders were helpful with generation three back in 2014, but starting with generation four (now called “Z wave classic“) pretty much any mains powered z wave device except smoke sensors will also act as a repeater and improve your mesh to exactly the same degree as the single purpose extenders do. So as @nathancu mentioned, most people just get any plug in or hardwired zwave device, whether it’s a light switch, plug-in pocket socket, plug-in sensor, or even a Z wave lightbulb. They will all work as repeaters. 
That said, there is a separate issue with the ring devices because they are using the newest Z wave security protocol, S2, and a lot of the older Z wave devices don’t support that. So that’s one reason that ring came out with their own extender, they wanted to make sure that their battery operated S2 devices would have an appropriate repeater. However, it turned out that with the final release S2 devices can use older devices as repeaters as well.
You can tell whether devices support S2 or not by checking on the official Z wave alliance product site:
All very helpful. Almost all of my devices are battery powered so I can see how getting some devices that plug in will strengthen my Z-wave network.
I am wondering if there is a particularly powerful Z-Wave amplifier device I should be on the look out for?
Also, I am not aware, is there a standard measurement of the strength of a Z-Wave amplifier device?
They almost all operate at the maximum value allowed these days. That wasn’t true back in 2013, but it is now. So you don’t have to worry about finding one which is better than another.
Remember that Z wave is intended to be a low power low traffic network. The way you expand coverage is by having more devices, as each of the repeating devices will pass along messages intended for others, sort of like the Wells Fargo pony express system.
The following FAQ should be helpful. Start with post 11 in that thread, read that, then go up to the top of the thread and read the whole thing. The topic title is a clickable link. 
Thanks again. Very helpful.