MSE for Windows 7 is basically anti-spyware and Microsoft has pretty much ceased development on it. They recommend using a 3rd party anti-virus.
If the clients are using Windows 8 or Windows 10 then use Windows Defender. This has improved considerably in AV comparatives Real World Protection test, especially for Windows 10. Use the chart and check April and previous months.
FYI. Avast purchased AVG so I would expect some merging after a time.
Some Free Alternatives
Kaspersky Free 2019, which was just released, is very good other than the political rants on it. It includes SystemWatch which will revert changes done by Malware. The con is most setting are locked.
Bitdefender Free is another good choice. It has a very minimal interface and is basically install it and forget about it.
Finally Panda Dome Free but it does contain ads. Kaspersky does not but it does have a News channel.
Note: Because Windows 10 is a service and Microsoft is constantly changing it's code, stick with Windows Defender included with the OS. Some AVs have problems keeping up.
Of the above I have experience with only Kaspersky free, and Bitdefender free
I use Qihoo 360 Total Security on my XP computer because the CPU does not have the SSE2 instruction set and I have found this is the only decent AV that will work on it.