Ok, after a reading a TON of arguments on the "best" free antivirus, I have come to this conclusion:
AVG: it still has its followers, but has really decresed in popularity, mainly due to its "bloated" size and speed.
Avast and Avira: to the best that I can call, these are the big two. If I had to choose one, based solely on what I have read, I'd have to say that avira is just a shave better that Avast. They both have thier pros and cons; the main ones are:
Avast:
Pro: multiple updates per day
more configuration options
no (obtrusive) pop ups
features anti spyware
Con:
ugly user interface
Avira
Pro:
top virus detection and good filepath following (there is some debate on this, but I heard this claim way more about Avira than Avast)
clean user interface
one "user review" poll had avira ranked slightly higher than avast after about 110 votes. They were the top two contenders on the pole.
Con:
really annoying pop up after each update (this can be fixed; do a Google search)
updates only once per day
some say that it offers no anti spyware protection while avast does; however, I just looked at it on their site and it says it does protect against anti spyware.
no firewall
Although Avira has more cons, they seem to be either easily fixed or inconsequential. It is a really really close race for both of them, but I'm going to have say that I'm going with Avira, simply because I have heard many say that it offers the best detection rates and also that they appear to have added spy-ware protection. I can live with the "no firewall" thing since windows has one built in anyway.
I'm only determining this from what I have read, if anyone else has anything to add, please do. In the end, it looks like you really can't go wrong with either of them.
Now, should/can you run a free malware/ad-ware/spy-ware program if your anti-virus already has one?