Hi,

Gdata total care - Never tried but heard its a Resource hogger as it uses two engines of BitDefender and Avast.

Kaspersky Internet Security - Fast boot up, doesn't slow down browsing speed considerably as other and needs high resources.

AVG Internet Security - Never tried, but tried there Antivirus, it was of kind ok didn't tried detection, Interface is sluggish but doesn't matter.

BitDefender Internet security - huge installer,small initial update,slow boot up,slow browsing speed,better Interface,High on resources and Excellent detection.

Just my two cents