Please recommend me the best antivirus software and web browser?

Hi. I'm looking for the safest web browser and antivirus software! I've been using Kaspersky Antivirus 2011 for my antivirus program and I did not have any problems with it. Should I buy the new one or a different company (is Bitdefender better?) ? And for my web browser, I can't tell if Firefox is better or Chrome. I watch a lot of videos, so which one uses the least amount of CPU? Which is overall the best? Thank you!