What's the most user friendly antivirus that doesm its job?

I would welcome opinions about what's the most user friendly Antivirus Program.

All the following are good.

AVG Free
Avira Antivir
Avast
Comodo Internet Security

I prefer Comodo or Avira, but I'm sure you'll get many different opinions.

Edit: I no longer recommend Avira because of it's new nag screen process. They deliver avnotify.exe with each update so there is no way to block it any more. It's a good AV program but the nag screen makes it very annoying and therefore not longer in my list of recommended AV software.

IMHO it's a 1 horse race, Avast is the clear winner for those requirements, AVG is OK but is no where near the other options, and Avir and Comodo are both excellent protection, but they are more complex to set up than Avast (Comodo as a firewall anyway), and Avir doesn't cover real time file transfer unless it's the paid version, you have to physically scan the file when it's downloaded unlike Avast that does it in real time.

Avast is my choice… But all the programs ZTruker mentioned are good. My experience with Avira was that it worked very well with its heuristics detection, which was good for me, but would produce false alarms. It also has some design flaws that slow the computer down significantly during certain things. They may have changed that by now. One instance is when you open explorer and navigate to a folder that has a lot of files in it. Avira appears to scan every file in the folder when you navigate to that folder which slows the computer down significantly. Where as, other anti-virus products, only scan the file if you mouse over it or attempt to access it in anyway. It also seems to have a slower scanning engine than others. Again, I used an older version that was from a couple years ago before I gave it up for the newer versions of AVG and Avast. AVG, although a good product, since 8.0 has caused me several headaches on computers. I now remove it and use Avast as standard practice to save form having any headaches. 8.0 has suffered from several failures that have caused certain portions of it to stop working. I also was extremely tired of it complaining about a failure to download updates, which is the fault of none other than Grisoft who has not given enough bandwidth or server power to support their free product properly. Version 8.5, from what I have seen has several performance issues. It has become so bulky now that it makes a significant impact on the performance of a computer.

See my update, I no longer recommend Avira, explanation in the update. I just uninstalled it and installed Avast and immediately disable the voice junk. I've not used it before so I'll reserve judgement until I have some experience with it but everyone that does use it says it's good.

Aww, but the voice junk is so cool.

Yup! Ranks right up there with the Lexmark voice Junk

I hate intensely dislike talking computers.