I just noticed in your signature that you are using Windows 8.1, so unless that needs updated, much of what I posted may not apply.
I only used Win 8.1 briefly on a new laptop, so I do not know it very well. But it was the start of MS trying to make the Windows OS more of a cloud based, mobile device.
I quickly upgraded that PC to Windows 10, and then discovered this. I have a Microsoft account using my gmail address, that stays logged off. Since I don't use any of Microsoft's cloud services or apps, or the Windows store, there is no way I need to stay signed in to make it easier for MS to collect data about me.
A local account is what it has always been since the early days of Windows. Just your user ID and password for the Administrator account on your PC. But if you change Windows so that you sign into it with your MS online ID, called your MSA (Microsoft Account), that's the way your PC login will continue to work.
Here's an article that probably explains it better than I can on how to revert to a local account if you're using a MSA.
https://www.theguardian.c...-account-in-windows-10or this
http://www.techrepublic.c...account-in-windows-81/and this
http://www.howtogeek.com/230543/how-to-revert-your-windows-10-account-to-a-local-one-after-the-windows-store-hijacks-it/ For protection, I use Avira. It is light and stays out of the way, if you set exclusions to real-time protection for selected processes, files, and folders. Avira Free is as good as the pro version. I have used both and they are both good. No conflicts here.
I am testing Bitdefender Free 2016 on another computer. I like it, but it has no file exclusions, so I just click off the real-time protection unless I go online with it. Bitdefender is among the few products (including Avira and Kaspersky) that frequently score 100% in malware detection tests. So there you have it, Avira Free and Bitdefender Free. Both top-notch detection engines are free. Since you stay offline mostly anyway, you can just keep real-time protection off for either, unless you are updating something.
Of course, by saying this here, there is bound to be a pile-on now in favor of Defender, Norton, Avast, Bitdefender, etc. LOL! But personally I would trust any of them, including the free ones, over Defender any day.