I think for the purposes of antivirus software, trust issues can be set aside here. Windows Defender ideally has the upper edge for choosing an antimalware solution for Windows in that it's baked in directly to the OS and therefore has more control and ability to prevent malicious activity than a third-party solution. You might not have to trust Microsoft due to privacy concerns, but for something like antivirus software that protects their operating system, intentionally making Windows Defender inferior software just isn't within their best interests.