Basic virus recognition of free and payware versions of one and the same suite may not differ that much, but there are serious differences in functionality. It can lead so far as that the free scanner does not track the system constantly in the background, only is a passive scanner checking the hard drive once you manually triggered it.
Also, a good secureity suite is much more than just an AVB scanner.
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A statistical meta-analysis - a simple count, that is

- found that Android is the one operaiton system of 2016 featuring the most security holes over the year, followed by - unexpected at least for me - Linux Debian.
The company featuring general software products with the most security holes over the year, was Adobe, followed by Microsoft. - I have stopped touching Adobe stuff already before I fled from Microsoft. There is only one good advise regarding Adobe software - DONT TOUCH IT.
NEVER.
The problem with Google software is not so much security, its Chrome browser has the best update rate in the business, no other browser gets patched as fast and as often - Google's problems are about privacy. I rate that as security issues, while many comfort junkeys obviously do not.
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I again advice to take the lists of AV Institute- which does not get "supported" by any commercial player or comnpany, and is apparently indeed independent - as orientation. I have seen them covering the ups and downs of trends with past titles I used pretty well, covering my own experiences with typical problems of this and that title.
https://www.av-test.org/en/
And since I recommended Malwarebyte's Anti-Malware repeatedly over the years, which indeed is very good: be advised that the new Android version for it does not convince. I tested it on a tablet and a cellphone, and an passive scan of the limited software installed on these devices always lasted for over one hour. Compared to the PC scan, that is hilarious. - On PC, use MBAM parallel to another AV/Security Suite, it is designed to be used parallale to one, and as I said, MBAM really is very good. Use the comemrcial version, it monitors your system constantly in the background. The popular free version does not do that.
Finally, understand that all this stuff does not make you
"safe" when you continue to behave stupid. It reduces the probability that something hits you - not more, not less. So better be a bit paranoid than sorry.