My opinion:
If you are searching for free protection for your PC Avast is a far better choice than BD free. I have used it for years and did not have problems. Also it's the most used free AV and maybe the most used AV in general at this time and most users find it fine. Don't forget about common sense though (don't visit sites that can be considered as risky etc). Some users report some bugs but this does not mean that it's unusually buggy in contrast to BD for example. More users means that the portion of problems will "contain" a larger amount of users having problems. Also BD is said to causing problems to many people's computers.