For free protection you can't get anything better than Avast Free or Microsoft Defender free.
Kaspersky free of course.
However, avast and Bitdefender are both great. I really like Bitdefender attack chain diagram when detecting a threat, but the lack of pure anti-ransomware module in the free version is way too much nowadays. Maybe if combined with AppCheck it would be a good combo.
Otherwise, WD + DefenderUI/Configure_Defender and Windows/Malwarebytes Firewall Control and AppCheck would be a great combo as well.
I personally use Comodo Firewall and Kaspersky Free with my own settings (whitelisting each other, turning off unnecessary modules) for over a decade, and it feels great (despite Kaspersky found it as incompatible app). Comodo himself is not needing support anyway, but I like Kaspersky KSN (over Comodo Cloud), Kaspersky System Watcher (rollback) and definitions, so that's why I'm preferring this over CIS. But to each their own, I guess.