RE: avast! Free with Comodo Firewall vs Avira Free with Comodo Firewall vs MSE w/ Comodo
Avast, avira and MSE are all good products but currently avast seems to be one step forward. However, if you can master the HIPS part of Comodo Firewall, the Behavior Blocker included with avast might no longer be needed - you can choose to not install it if you do a custom install of avast. Same goes for the avast sandbox that you can disable in settings.
As for avira, I used it for a long period of time but I encountered some issues that made me switch to avast... false positives, a component failed to start after an update, etc. I haven't used it since so things might be different now.
MSE is a good av but uses allot of RAM and scans are slow.