Recently I heard a discussion that recommended Windows Defender over third party alternatives since Windows Defender didn't add any new attack surfaces to Windows, e.g. Symantec.Now even Google engineers are promoting Windows Defender for similar reasons:
Browser makers don't complain about Microsoft Defender because we have tons of empirical data showing that it's the only well behaved AV. https://t.co/ClGwEWCoWuAnd it's free.
Google engineer, Justin Schuh
And it's fast.
And it's quiet.
You could do worse.
For an alternative view, read this.