While I do have McAfee running on two separate machines, one is the Internet Security with tweaked settings which does protect the standard user (as mentioned in the thread by Huracan). The other Machine is actually running McAfee Endpoint solution (McAfee Security-as-a-Service (Saas) which comes also with a Firewall and some other modules that are far better than the IS modules. Both use the same signatures but its modules are more polished on SaaS versions at the cost of its price.
Last time I played with Avira IS, its Firewall component did cause me some issues and performance of the solution was affected as it didn't seem to get along with my Windows 7.
Avast, used to be running on the system until around version 8 and I basically gave up with random issues. That included some BSODs, slow downs etc. Some features of the IS were good but then again, I had to weight if it was worth the hassle.
In the end, if avira works fine for you go for it. If you prefer decent protection and rich features (which some consider bloat), then avast. If you care to tweak a bit the solution, then McAfee.
On a side note: McAfee ain't as bad as many say. They did improve a lot. Only reason I do not run SaaS on my main gaming system is because of the firewall pop up (sliding from bottom of screen up and it never popped up when a new rule was to be created (i.e connection was made), but with a slight delay. Also it does require the use of webdamin to configure all the modules and policies (bit of a hassle for my own system), but then again I can remotely configure it for other systems associated with my account.