If your intention is to get non-biased opinion rather than finding it entertaining to see both side of fanboyism, either here or Avira boards may not be suitable places especially after the questionable domain name issue
, which is definitely off topic in this thread
So, "politics" aside, as products, of course, both of them have their cons and pros, which is why I'm a user of both products.
Generally spaking, Avira keeps one of the highest detection rate while this is true to the rate of false positives. So, if you are unfamiliar with dealing with possible FPs, I don't recommend the product toyou. Avira Personal is a simple product, which just does its job as an anti-virus application. Its main focus is its resident scanner, which can detect both virus and spyware while Avast! Home has more features to prevent malware from entering the protected computer, by Web/Internet/Mail/PnP/IM Shields, beside its resident scanner called File System Shield. That said, Antivir is pretty quick at reacting to malware and the difference coming from the lack of these features may not be as significant as you may imagine. Avira Personal is infamous of its nag screen which pops up whenever it finds a download while Avast! Home only has a nag screen embedded in its interface. Some people seem to have written about the update server issue of AntiVir but, at my end, it has been significantly improved, which makes its frequent update another pro for Antivir although this means the frequent nag screens. For support side, AntiVir boards are rather restrictive compared with the boards here but, as I have written, its a simple product and I haven't needed too many help from their boards.
I have written mainly about Avira Personal since you will find enough information about Avast here. So, now it's down to your needs/preference.