To start with, you must know all AV will make use of your system resources, and will (some more some less) slow down your daily life. As well, you must know now that today, almost all well-known antivirus suites do the same job. Malware detection ratio based on signature databases are really poor nowadays, and mostly every antivirus does a similar job. Some of them will detect more samples than others, but that's it. So, answering to your question, i would not choose the best according to "Market Reviews" like PCMAG, or even AV-Comparatives. I would choose the one that suites the best with my host PC. Forget about less-known antivirus that are not mentioned on this forum. If our testers do not try one on the HUB, much probably it's not worth it. (like it happened when i tested Immunet on the Hub, stay away from it). Then, once again, you realise you're on a standby: you have lots of well-known antivirus, such as AVG, Avast, Avira, BitDefender, ESET, Kaspersky, Norton, Emsisoft, and lots more. Since all of them are sig-based software, i must say that the key is on software combinations to cover all your system's weak points. For example, just before winning Avast Premier GiveAway here, my configuration was simple and effective: Avast Free (really light, tweaked for maximum protection), ZoneAlarm Free Firewall (adjusted on notify me everything), and HitmanPro.Alert to protect me from Xploits and vulnerabilities. That's a good safe combination, that can help me with having a sig-based antivirus.
So, i would say: choose the one you like the most, not the best one. That one that fits the best on your PC, not the one which Av-TEST says has the best real time protection. If you have an old hardware, i'd choose 360 Total Security, Sophos, or Avast. Complementing it with a light free firewall, and you're done boy.
To conclude, do not satisfy yourself with default software. Every time you can, tweak. Tweaked settings will give you the best protection you can recieve from software. Stay safe.