Used to run Malwsrebytes as primary and defender occasional scans but when I recently reset my rig I skipped Malwarebytes and run defender only. Seems to do the job well.
Malwarebytes had a high rate of detection of questionable behavior of websites. Not sure if these flags were real.
Just last year I cleared infections from a computer using Malwarebytes Antimalware and Windows Defender was acting hilariously throughout the scan. As soon as Malwarebytes Identified and cleared an infection, Windows Defender would pop up a notification right after saying "Infection found!". It was too funny. I do have to say that Defender has gotten better lately, but Malwarebytes is still my "go to" for making sure a machine is clean from infections. I don't need it for real time scanning though.