Before I chose various AV such as Norton IS 2013 Webroot and Kaspersky IS 2013 2013 for 30 days, but now I am satisfied with MSE v.4.216. It is sufficient and hunting all malware and then updates the database frees a lot of RAM.
All vendors take different approaches, some lower scored product contain interesting features such as Panda Cloud and it's Data Shield. Pick what you choose.