In modern times I'd actually say if you're unwilling to pay for a premium av probably best with none.
As long as you're not an idiot with how you act on the internet the bulk of the issues a free antivirus would cover are either things windows defender can handle if you're a little cautious (personally I actually turned that off) or things that would still get through that a manual virus/malware check would be required to sort.
I mean 5 years ago or more I woulda said just get something like avast as it used to be unintrusive and good but now it's maybe 90% based on do you do dodgy shit on the internet? Y/N and the bulk of the other 10 is bleeding edge virus'/malware which most antivirs won't pick up on for a while
Also ditto to the guy above me... only really started paying attention to the av stuff when I was 15 or so (over 6 years ago) and by that point norton had become an insane system resource stealing pile of magikarp that actually missed things that avast picked up on when avast used like a 100th of the resources nortons used...
This is an article published back in August but does an excellent job of summarizing Windows Defender.
Is Windows Defender Good Enough?
How to Use the Built-in Windows Defender Antivirus on Windows 10
Windows 10 has built-in real-time antivirus, just as Windows 8 did. It automatically runs in the background, ensuring all Windows... [Read Article]
Antivirus is already running out of the box. Windows Defender automatically scans programs you open, downloads new definitions from Windows Update, and provides an interface you can use for in-depth scans.But how good is this? Well, truth be told, Microsoft’s antivirus is a bit behind the others when it comes to comparative antivirus software tests. We’ve sounded the alarm on this before, and we were particularly worried because we had previously liked Microsoft’s antivirus product so much.Windows Defender has a lot of advantages. It’s built-in, won’t harass you with pop-ups and requests for money, and is lighter than some competing antivirus solutions. It won’t attempt to harvest your browsing data and make money from it, as some free antivirus programs have started doing in an attempt to make a profit.Overall though, Windows Defender doesn’t provide bad protection. Assuming you keep Windows up-to-date — which happens automatically now — and use an up-to-date browser, avoiding potentially dangerous plug-ins like Java — you should be okay. Windows Defender and with the standard computer security practices you should be followinganyway do a fine job.
Despite the low “scores” offered to Windows Defender by AV-Test — just “0.5/6” for protection — Windows Defender caught 95 percent of the “widespread and prevalent malware” in June 2015, along with 85 percent of the zero-day attacks. BitDefender managed 100 percent and 100 percent of the tested samples, while Kaspersky managed 100 percent and 99 percent. So, despite the wide difference in scores, Windows Defender still does a solid job. In the past, Microsoft has alleged that it focuses on malware that’s actually prevalent in the real world while the tests aren’t representative and other antivirus vendors tune their products to do well in tests. Microsoft employees don’t generally comment on test results anymore, however.
Windows 10 also includes various other protections introduced in Windows 8, like the SmartScreen filter that should prevent you from downloading and running malware, whatever antivirus you use. Chrome and Firefox also include Google’s Safe Browsing, which blocks many malware downloads.Windows Defender should probably be fine for most PCs, along with some common sense and other good security practices. However, if you’re regularly downloading pirated applications or engaging in other high-risk behaviors, you may want to skip Windows Defender and get something that does better against the collection of obscure malware samples used to test antivirus software.
We also recommend an anti-exploit program to protect your web browser and plug-ins, which are the most targeted by attackers.MalwareBytes Anti-Exploit is the free program we recommend here. It functions similarly to Microsoft’s own EMET security tool, but it’s more user-friendly and offers more security features. This helps block common exploit techniques, even if they are zero-day attacks that have never seen before. MalwareBytes Anti-Exploit would have blocked all those nasty Flash zero-day attacks you heard of recently, for example. It hardens your browser, plug-ins, and other targets attackers frequently target, defending you against the most common attack techniques rather than attempting to catalog and defend against every known piece of malicious software.
Windows Defender plus MalwareBytes Anti-Exploit is a good, free, low-hassle combination of security programs we recommend to keep the average Windows 10 PC secure. Enterprise Windows 10 PCs would often have Windows Defender running along with Microsoft EMET, but Windows defender and MalwareBytes Anti-Exploit is a better combination for the average home PC.(MalwareBytes itself is a solid anti-malware program that functions well as a compliment to any antivirus program, including Windows Defender. It finds a lot of the “potentially unwanted programs” (PUPs) and other junkware that a typical antivirus won’t find, but MalwareBytes Anti-Exploit is a separate program.)But What’s the Best Antivirus?
Okay, so maybe you aren’t happy with Windows Defender. You might want to select another antivirus instead.If you’re looking for a paid antivirus product, Kaspersky and BitDefender are consistently ranked up there at the top of the various antivirus tests. You might want to do a bit more research orexamine the latest versions of the tests yourself and see which antivirus programs are doing the best. But Kaspersky and BitDefender are both solid, well-respected options if you’re prepared to open your wallet.BitDefender also has a very nice free edition if you don’t want to spend any money, though it’s quite barebones. Avira’s Free Antivirus is also very good, scores highly in tests, has a lot of options and doesn’t have very much nagging compared to other free programs (just be sure touninstall its browser extension).
There are other great free antivirus programs out there as well, but be sure to avoid installing whatever toolbar or browser extensions the antivirus wants to install. Most free antivirus companies have turned to bundling software and harvesting data to pay for those “free” solutions.Windows Defender will automatically disable itself when you install a third-party antivirus, and then re-enable itself again if you ever uninstall that third-party antivirus. It’s designed to get out of the way.Whatever antivirus you choose, it won’t provide complete protection. If you download and run harmful programs, you’re going to end up in trouble at some point.
Selecting an antivirus that has better protection scores against obscure malware you may never encounter may help make you a bit safer, but other security practices are more important. Ensuring you stay safe and keep your system secure is more helpful.And, considering the scariest attacks these days are zero-days that use holes in browser plug-ins and plug-ins themselves to compromise your system, MalwareBytes Anti-Exploit will likely offer better real security against the actual most dangerous attacks than a replacement antivirus.
My security is as follows:
Hitman Pro Alert
I also run 2 rootkit scanners but they're on-demand only, Kaspersky TDSSKiller and Malware Bytes Anti-Rootkit (still beta)
They play well together and don't impact my resources too much.
Avast Free is outstanding, as is MalwareBytes Free. That said, I use BitDefender. The way they handle billing is a frustrating process and their customer support is kind of a hit or miss. However, BitDefender is consistently rated as among the best or the best, and over quite a few years they have maintained their edge over most other companies. Not many makers have that much consistency, and BD's scanning engine is almost unparalleled, and it shines really bright when it comes to protecting against ZD attacks.