You're mostly right
Combofix, Malwarebytes, Spybot - top 3. AVG - not so much (ever tried installing the last few iterations of it? Requires a special tool to remove it most of the time and you SHOULD uninstall it because it doesn't work worth a hoot). Avast - just so-so. Microsoft Security Essentials blows away both AVG and Avast and it's free, too, and I'd place it at number 4 on your list. After that lineup, who needs number 5?
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