Kaspersky wasn't an option to the poll so I selected other. I can't imagine anyone using windows defender... Ever. It is one of if not the worst there is. All WD offers is signature protection, and its signatures are absolutely usless. You are better off guessing whats malicious or not than trusting WD. Any other free alternative is better.
IMO the best free set up is Sophos Home + Comodo Firewall. Comodo is arguably the best free security solution out there. The only area Comodo fails is in signatures, but thats where Sophos comes in. Sophos has some of the best signatures, so this will make up for Comodo's terrible signatures. Comodo is known for its firewall, auto-sandboxing, and HIPS. IMO every free configuration should have Comodo, assuming it doesn't interfere with anything they are doing.
Conclusion: Sophos Homes + Comodo Firewall is the best free configuration you can have. (At least from what I've seen)