AVG and Malwarebytes. Don't use the performance junk, only run the web scanning if you are "at risk" (kids, others who don't understand risky sites or are click-happy, LOL)
Be aware that AVG now has a "Deep Scan" which is the original scan. Under the settings gear, choose this initially and at least once a month.
Run both programs' scans once a week, or any time you have something odd, risky, or suspicious occur. MUCH easier to be proactive than to fix it later.
The above two programs (free versions) behave well together. Be sure to remove McAfee, Norton, etc first. MS-Essentials usually gets out of the way on its own, except for a few temporary versions/updates in the past.
Consider this professional advice ;)