Avira always seems to be at the top of the charts on http://www.av-comparatives.org/. I have used it for years without issue.
You could create a "Standard" account for your day-to-day. Then no need for virus protection. ^_^ To install software, you'll have an extra step of typing in the admin user name and password. Nice.
Just use Windows Defender. It's built in. You're already done.
Avast free, but NOT for the antivirus. It has a really convenient software updating utility which will make you far more secure than any antivirus feature ever could.
Nearly every piece of malware I see rates 0/51 on virustotal. I would recommend picking one of those that has a high detection ratio, but you see...
Try ESET Smart Security, they have a 30 days free trial period.
BitDEfender
Use Mac OSX
After I stopped using Windows I've revisited my definition of "works well". Not trying to troll or bash Microsoft here and perhaps you have strong reasons to stay on it, but sometimes people try to treat symptom not the problem.
I only trust Windows Defender from Microsoft. 1 - They know the internals of their own system. 2 - They have strong interest in keeping your OS running well. 3 - it is free.