+ reliable software developer
+ basic version of antivirus is freeware
+ rather high detection capabilities
+ free updates

No noticeable downsides. But beware, that NONE OF antivirus programs could guarantee 100% protection of your computer. And remember one more thing: ANY antivirus SLOW DOWN your puter. More or less.

PS I prefer not to use any antivirus applications on my laptop. But i am using trusted sites on the internet and from time to time check my PC with on demand scanner. Hate those residential thingies. 

PC version
Android version

PS Installing antivirus on android is optional, because quantity of viruses for this platform relatively small, so i don't bother with installing. But if you are a easily carried perfectionist....