[1nT0x!c@t3d]

I would advise against paying for any AV.
Source: I've been working in IT for years, and while I have to tell them to use Avast I don't think it does much good.

My strongest recommendation would be the following
1) Download and Run Malwarebytes AntiMalware once a week or so
2) run HitMan pro as a second opinioin
3) turn on windows defender
4) install Comodo Dragon or Ice Dragon and use their DNS
5) in either of the above, make sure you have adblock with the malware filter list to auto-update. limit any and all add-ons you are using and only use them if they are from a trusted source.
6) be careful of what you download, and if you need to download something and you aren't sure of what it is, upload it to virus total before you install/run

AVG / Norton / and the like will slow your system down. They don't have the best detection rates and even those that do can't and won't detect everything all the time.

7) and this one might be the most important, back up your data!

Best of luck.