Some of the features I have liked about Avast for the past several years are a boot time scanner
game mode, temporarily disable for specific time, disable until system reboot .
..which can quite handy when running a dif scanner aka [Malware-bytes]
it uses much less resources than AVG as other have mentioned
update it's definitions daily on sys startup
& detected suspect files that some others missed 'I know cause I put them there' to test
The only minor detail encountered by new uses is to simply just register with Avast within 30 days and enter the license key
NOTE : thanks realneil for the correct info :" The Boot Time Scanner is gone with Win 7 64 Bit installed.