Combofix and Hijackthis are both post malware infection cleanup tools.
They do nothing to prevent infection in the first place.
An anti-virus program is suppose to catch viruses before infection occurs, much harder to do.
As for who makes the best anti virus software, that's a matter of opinion and not one I'm going to open the door to in this thread.
The best defense against infection is safe surfing habits and common sense!