Well, why not Bitdefender + syshardener, then?
If the price and the heaviness of BD doesn't bother you, I think that's a pretty solid setup.
BD is more intrusive to the system (and thus more likely to conflict with other softwares), and will probably leave more remnants after uninstalling, but in terms of protection and usability, BD + syshardener should be great.
BitDefender plus nothing, it's a full suite and it's enough. If you want to rest assured, then Hard_Configurator or SysHardener will help you to tweak Windows configuration, but in terms of real time protection do not add anything else.
There's very little advantages to upgrading to Avast Pro/Suite/Premier, over Avast Free Antivirus - except for in-app upsell Ads. Bitdefender Free and Total Security have a few differences, so something to look into. But don't buy into Avast, it's a waste of time.
Over the two I'd choose Bitdefender, you can even utilise Syshardener alongside BD. BD should also stop PUPs, another web extensions would be unneeded.
When you have to think about computer security, think about what's better and runs smoother on your device. Asking on here via a thread was a fantastic idea. Gives you the knowledge of what solution(s) are good for you, to make a better informed judgment.