I like Avast free because of some of the extras.
Windows AV is probably good enough, make sure to set the settings and after you finish your full scan do a start up (offline scan) scan with it.
Avast free turned into an unexpected autopay $119.00 annual charge in my Paypal account. The fine print notes this charge but I still don’t know how they got my CC number. Charge is under protest/decline payment with my CC company. Watch out.