The comments above about there being no 100% best Antivirus... It's true. You will never find '100% protection'.
The closest I can think of you being able to get yourself there is to never download anything off the internet and to lockdown your system to only allow the execution of the pre-installed programs which come installed with Windows. (or to just stop using your system altogether...).
I recommend you pick a good, well known Antivirus/Internet Security product. Off the top of my head I recommend either one of the following: ESET Smart Security or Kaspersky Internet Security.
If you choose to use Avast Internet Security, they have a Safe Browsing feature which you could look into using when you need to do banking-related browsing or anything which may contain sensetive information.
If you decide to use a Antivirus program over Internet Security, you'll need a Firewall (if it does not already have one) if you would like that additional protection. You could look into Comodo Firewall, however you could disable the HIPS on it as it wouldn't be necessary when using an Antivirus program with a good HIPS/BB protection. Having both enabled could make too many alerts which may become irritating, and could be seen as unnecessary. (for example, Emsisoft have a well-liked Behaviour Blocker which does work quite well).
If you want protection based upon automated sandboxing of programs on your system, look into Comodo Internet Security. It has such a feature.
You may also want to check the detection ratio of a program on VirusTotal before executing a new download you are not familiar with to see what other vendors think of the sample. Please be aware that false positives are always possible.
For web protection, alongside running a good Antivirus/Internet Secuirty program with good web blocking (here I should note that ESET have a good reputation for providing very good web blocking - that's not to say the other vendors products have bad web protection) (malicious website blocking, phishing website blocking) you can also use a good adblocker to help prevent advertisements. Advertisements can actually invade your privacy: they can track you. Using a adblocker will help avoid this. I recommend using uBlock as your Adblocker. I use it myself; I have found it to work very effectively and it has never caused me issues. Since I have been a user of adblockers like Adblock Plus and Adguard, I recommend uBlock over those 2 extensions due to my experience being best with uBlock. You can also configure uBlock to work more effectively on the settings.
You may also be interested in the WOT extension for your browser. WOT stands for Web of Trust. It's a reputation based extension (gives reputation based on user reviews for websites). You can find more information about this extension at the following URL:
https://www.mywot.com/
You may also be interested in Click & Clean extension. Allowing it to clean your traces after using your browser is good as it does prevent any programs from managing to access such information (steal it). You can find more information at the following URL:
https://chrome.google.com/webstore/detail/clickclean/ghgabhipcejejjmhhchfonmamedcbeod?hl=en
You can also try out online services which allow you to submit a file for analysis. Some examples of services which can do this are:
You can then check the report after it's analysis and decide based upon the report if you wish to run the program on your main system.
Cheers.
