The improvements to Windows Defender, now Windows Security as of Version 1809, have been huge over the last several years, and the results of third-party lab tests indicate this.
Although I have Malwarebytes on my system (free version, manual scans) too, I cannot even recall the last time I used it. It was always a backup tool for the "in case I somehow become infected" circumstance, and I have not had an infection on any of my systems in probably 20 years or longer now.
See the most recent plus the last several years of historical test results from:
(Reports Page)(360 Protection Testing Category)
Brian - Windows 10 Home, 64-Bit, Version 1809, Build 17763
A great deal of intelligence can be invested in ignorance when the need for illusion is deep.
~ Saul Bellow, To Jerusalem and Back