Hi Hexter,
There are two major types of AV product: "consumer" and "enterprise":
Consumer - standalone AV or security suite, managed by the PC user, updated directly from vendor's servers.
Enterprise - licensed software in blocks of 50 (or whatever qty) AV or security suite, AV client is managed and updated from a central server at Corp HQ, usually locked down so PC user can't turn it off or modify it's settings, often have IPS functionality, sometimes include remote OS and application patching utilities.
The key differences is Enterprise software is managed from a company-owned centralized server. That way the IT staff (incredibly skilled and under-rated professionals !) can be 100% sure your PC AV client is: i) receiving signature updates, ii) being patched/upgraded and iii) are alerted if you have a virus and will engage to help eradicate it if the AV suite can't. Also, if it's a full security suite, they can control what sites you visit (content filtering), maintain your firewall and VPN settings and keep logs on what Internet sites you are visiting (even if you are not on the corporate network) among other security features.
Are you looking for advice on consumer or enterprise grade? Do you need a simple AV engine or a security suite?
My suggestions:
Consumer - Free software: Avast, Avira or AVG
Consumer - Paid software: Norton, Bitdefender or Kaspersky
Enterprise - Paid software: ESET Endpoint (aka NOD32), Norton Antivirus (aka Symantec Corporate) or McAfee VirusScan Enterprise
There are many other very good products, but the above are the ones I have experience with and are consistently rated in the top 25%.
Please note: The above product names change every year, mostly for marketing reasons. You may have to cross-reference the older names I'm using.
Also suggest you augment the above with:
SUPERAntiSpyware -
http://www.superantispyware.com/
Malwarebytes Anti-Malware -
https://www.malwarebytes.org/
Do not configure the above to run in the background. Just do manual scans. Otherwise there is a risk of AV engine conflict and the slowing of your PC's performance.
I'm not a Windows Defender / Security Suite fan. In the past windows native products consistently rate on the bottom of the list with poor detection and eradication test results. I understand they have gotten better in the last year, but why risk it if there are better free products available?
Here are a few independent test labs offering testing results:
http://www.dennistechnologylabs.com/reports/s/a-m/2014/DTL_2014_Q2_Home.1.1.pdf
http://www.av-test.org/en/home/
http://www.av-comparatives.org/
https://www.virusbtn.com/index
Here'a a great chart to get you started:
https://www.av-test.org/en/antivirus/home-windows/
Note that there is a tab for each OS.