Oh well, it's too late now, Avast is already installed 
The new AV's behaviour just weirded me out and made me lose trust in a program that I was using for years now. That huge ad on every update didn't make things look better either.
On the topic of desktop firewalls: I don't use any because IMO they are useless besides controlling what programs are allowed to communicate with the internet, and even then the Windows FW manages to do that so I don't need an extra program for this task. Also I'm sitting behind a router so most internet annoyances don't even come through anyways.
The new AV's behaviour just weirded me out and made me lose trust in a program that I was using for years now. That huge ad on every update didn't make things look better either.
On the topic of desktop firewalls: I don't use any because IMO they are useless besides controlling what programs are allowed to communicate with the internet, and even then the Windows FW manages to do that so I don't need an extra program for this task. Also I'm sitting behind a router so most internet annoyances don't even come through anyways.