"The free ones can't have the resources to find and fix everything when so much is coming out"
With the exception of Comodo, which is funded via other routes, all the main "Free" anti virus are free license copies of commercial products, so the resource issue only doesn't really exist.
The only exception to this is ClamWin which is opensource and strangely passed the av-comparatives test.
When it comes to testing I prefer independent tests such as that at VirusBulletin which keeps giving avast! & AVG 100% on its tests.