My names Mark, and I am going to comment and provide suggestions on your configuration to help you.
Before I get started, I should probably let you know that there is no such thing as "Malware Bytes" or "MalwareBytes"! Although, of course I know what you meant; you have Malwarebytes Anti-Malware installed for on-demand scanning. No worries, I just thought I should mention that spelling mistake (if you forget, it won't matter - everyone should be able to identify what you meant).
It's great to see you have UAC (User Account Control) enabled on your Windows machine. I see many people disabling it - make sure to always keep it enabled. While people disagree that it provides protection to the user, in reality is does. UAC is there to stop a program executing which will have permissions which are seen as a potential safety risk. For example, an application without the correct rights won't be able to things it wants to do/will have restricted access to things it may want to do. If UAC was disabled, a program could be executed and do anything from modifying/creating/deleting registry keys, dropping files into System32 (which is actually more common than someone would think) to loading Kernel-Mode drivers (rootkit developers usually prefer this, however of course there are plenty of user-mode rootkits) and creating scheduled tasks (a scheduled task is setting an action to occur at a certain time. This is achieved with the Windows Task Scheduler; for example, a program may create a scheduled task to have itself started up automatically at a certain time in the day). There is a lot which can be done without the user consent whilst UAC is disabled. In fact, if a program has Administrative rights, it can then disable UAC altogether through a tamper with the registry key EnableLUA (under: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\policies\system). If the value is set to 0, then UAC will be disabled. If it's set to 1, then UAC will be enabled. To see another example relating to the UAC EnableLUA registry key, check the following spoiler:
Your system may be loaded with malicious software which may first proceed to disable UAC once running with Administrative priveleges. After disabling UAC, they may execute a downloaded Trojan (let's say that this particular threat is a Trojan Downloader, therefore it downloads other samples) with Administrative rights. Only difference is, UAC was disabled, preventing the user from being alerted of the execution to this process.
So make sure you never disable UAC. It's a critical feature in Windows which should be kept enabled.
I believe Avast Free is a good choice for an Antivirus, and there are many satisfied customers. I assume you are satisfied with Avast's performance since you have never been infected, or did you recently change your Antivirus product installed on your system? Nonetheless, since you have never been infected you are doing very well.
ESET Online Scanner is a great on-demand scanning tool and works very well. It's on the list of my recommendations for on-demand scanners. You may wish to add HitmanPro to the list of your on-demand scanners. It's scanner is very quick at scanning your system, it usually only takes a few minutes for me. It also contains the Bitdefender and Kaspersky engines, making it more powerful and effective at detecting threats on the customers system. If you win the ESET giveaway (I noticed you mentioned it above), you may wish to add another on-demand scanner to the list installed, and since if you had ESET, the Online Scanner on-demand would be unnecessary. If so, you may wish to have it replaced by either Emsisoft Emergency Kit or Zemana Antimalware. This would then either leave you with: ESET Online Scanner, Malwarebytes Anti-Malware and HitmanPro (whilt using Avast) and if you are a lucky winner to ESET you would then have: Zemana Antimalware/Emsisoft Emergency Kit, Malwarebytes and HitmanPro.
You may be interested in installing HitmanPro.Alert. It contains many features such as:
Alerts the user when critical functions of the browser are compromised by known and new banking Trojans, like:
Zeus
SpyEye
Sinowal (aka Mebroot and Torpig)
Ice-IX
Citadel
Cridex
Carberp
Shylock
Tinba
and many others...
Passively vaccinates the computer to make sandbox-aware malware belief it is attacking an automated analysis system, causing the malware the disable itself.
Supports all popular web browsers: Internet Explorer, Chrome, Firefox, Opera, Maxthon, Comodo Dragon, Pale Moon, Tor Browser, Avant Browser, Baidu Spark Browser, SRWare Iron and Yandex Browser.
Future proof technology does not rely on malware signatures.
Compatible with all antivirus programs and runs alongside any other security software.
Supported on 32-bit and 64-bit versions of Windows 8, Windows 7, Windows Vista, Windows XP, Windows Server 2012, Windows Server 2008 and Windows Server 2003.
For your Privacy software, CCleaner is a great addition to cleaning things from your web browser content to cleaning up issues found in your Registry. Please make sure to allow CCleaner to save a backup of your Registry before allowing it to clean it up, since errors can occur after using any Registry cleaning software. Even CCleaner. However, CCleaner users are very satisifed and usually have little to none issues after using the product. I myself have had an all clear whilst using CCleaner, as opposed to other products in which I've had issues after using registry cleaning features and had to manually fix/use a backup I had previously saved to fix it.
For your Backup & Recovery an External HDD is always nice to store personal documents/work related content, but have you ever considered the thought of if that External HDD became lost, damaged, or if the files being stored on there became corrupted? You may be interested in Cloud Storage for some things; if you have a Smart Phone usually the well known cloud storage companies provide a smart phone application which will allow you to access any files after syncing hosted on the cloud network from your phone. Usually this includes being able to manage the stored files.
You may like to add Sandboxie to your configuration. Sandboxie is a Sandbox. A sandbox will allow you to execute programs without them actually having any affect on your system. You can download it from the following URL: http://www.sandboxie.com/
It wouldn't hurt for you to try scanning new programs occassionally at VirusTotal before allowing them to run on your system, too. This will help you catch out a new program you feel is unknown or unsure of which is actually malicious software/adware/potentially unwanted. Please make note that it's possible for a false positive detection, so make sure a reasonable amount of AV engines or trusted AV engines detect a sample before automatically assuming it's malicious software/adware/potentially unwanted.
For your browser extensions you may like to add an extension called HTTPS Everywhere. HTTPS connections are secure since it encrypts the communication between your browser and the website. You can find more information at the following URL: https://www.eff.org/Https-everywhere
Out of interest, do you have any Adblocking software/extensions installed which you forgot to mention? An Adblocker is very important. It doesn't just help you by giving you an ad-free experience, but also protects your privacy in a way - advertisements can actually track you. blocking them prevents this. Based on my own experience with many different Adblockers from Adblock Plus to Adguard, among all the other extensions and software out there, I would rate uBlock the best (based on my experience, others experience may be different). You can find more information at the following URL: https://chrome.google.com/webstore/detail/ublock/cjpalhdlnbpafiamejdnhcphjbkeiagm?hl=en