Overall I would think AVG Free Antivirus performs better than Panda Free, although I have yet to try the latest version in the past 3 months.
Well in reality, cloud detection should perform better since the rapid of information can provide an accurate detection; however for Panda Free is different. (passive and behavior analysis is mediocre)
Meanwhile for AVG free is balance with standard signatures, some form of cloud and Identity Protection (BB).
I just fixed a client's computer that had AVG free on it. It's a single-core with xp; if any computer will show AV slowdowns, it's this one.
The computer was slow due more to AVG than its age. I replaced AVG with Panda free and Malwarebytes Antimalware free.
Malwarebytes & adwcleaner removed 130 items that AVG didn't flag (adware/spyware, nothing destructive). This is normal for computers brought to me with AVG on it. Perhaps if they spent more development time on malware removal and less on "clean-up/tune-up" junkware...
It runs the latest Firefox and Office 2003 just fine now. I don't know why av-test keeps rating AVG as high performance and Panda as low performance as my experience has always been the opposite.
I choose none but if I had to I would have to go with AVG since I have had issues with Panda literally crashing my system, and if I'm not mistaken Panda requires internet access for protection since it's cloud based.