Welcome to avast forums 
I too am am a refugee from Avira. Once I went to Avira V10, I couldn’t share my printer anymore (regardless if the firewall module was installed or not). One of the WinXP Pro boxes came to a grinding halt (way too slow). I trialed and installed AIS 5 and am happy (will be happier once Avast figures out the problem with their firewall module and Perfectdisk boot-time defrag).
Well the big difference between avast and avira is mostly about the resources used on the system which makes people to like avast more with its light and effective protection against malware
That’s what I think ;D