When comparing avast! vs Windows Defender, the Slant community recommends Windows Defender for most people. In the question“What is the best antivirus software for Windows?” Windows Defender is ranked 1st while avast! is ranked 14th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Decent anti-virus protection
Pro No Ads
Pro 100% Detection Rate (according to AV-Test)
As of March 2021, Defender has been scoring perfect 6 in AV-Test ratings in all 3 categories for almost a year. The last time it scored a non-perfect score was in April 2020 which was a long time ago.
Pro Part of Windows
Pro Lightweight
Cons
Con Tries too hard to sell you the paid version
Con Too noisy
Avast! has sounds turned on by default. It also has a lot of blinky features of questionable use.
Con Makes your system slower than usual
Even though scans are not being run in background, it will slow your system.
Con Opt-out installation of Google Chrome
These advertising tactics are simply unacceptable.
Con Selling potentially identifying user data
Con Detection rate isn't too solid
Avast! is not the sort of antivirus product to give you peace of mind. In practice, it does miss some malware every now and then. You'll need backup virus protection, which raises the question why you should get Avast in the first place.
Con Expires after a year leaving computer exposed to new viruses
Expires and stops updating after a year after which the user's computer may become infected by new viruses not covered by existing patterns.
Con May interfere with hyper-V
Since avast has its own virtualization engine, it will cause issues with hyper-V.
Con Unable to detect some adware such as FADE adware
Con Blocks or causes issues on apps or games
Con "Smart Screen" feature
When running an unknown application, avast will run it wrapped in a sandbox environment first for scanning, then kill the process and re-run it again. A lot of applications do not like this.
Con It doesn't even get anything
Con Harder to set exceptions and restore for false positives
Defender and its options isn't as accessible as other av programs.