For at least the last decade, at least for consumers, any type of anti-virus such as Norton, Avast, AVG had more downside that upside. Avoiding running under an admin account and using Windows Defender was better than installing any third-party anti-virus solution.
That is not entirely true, for ransomware your permissions are enough for them to encrypt your files. Windows defender is getting there, but I am not sure it is quite there.
I'm with the grandparent here, but want to chime in that backups are also important. If all my files got encrypted, I'd only be out a couple of days time.
Smart ransomware will wait weeks or months before revealing itself. So you'll have been backing up a lot of encrypted documents, and your last clean backup may be quite old. It may be totally gone if you're rotating quickly.
But I essentially agree that Windows Defender is about as good as it gets. It's not perfect protection, but neither is any other product.
MS Defender is not any different from any other AV products and it definitely has its share of issues; one of the reasons to get some other AV is just to get rid of Defender.
It still sends lots and lots of data home. The only difference is we don't know, if Microsoft is selling them. They surely are not selling them openly, but I would not be that surprised to find out they use it for other purposes as well. But they openly do tracking and show you ads in windows anyway ..
