no, you have to choose whether to stay with avast or CIS is that the suite
you can combine avast with comodo firewall.
The "best" is something very dear relative. The ideal security solution will depend on the user profile (basic or advanced), usage profile of the computer hardware configuration of the machine and user ID with the security software adopted. There is no single answer to your question, because as you can see it is not so simple.
Comodo now offers a complete suite with firewall, module behavioral technology in the clouds and many other supplements and it is free. Every Free Antivirus tries to give a basic protection to your computer, some companies give more resources to conquer the Customer.
As you can see this is very relative to each company, not all are equal.
Firewall in CIS this was the best of all this recent test released by Matousec site
http://www.matousec.com/projects/proactive-security-challenge-64/results.php
