You shouldn't look at antivirus without looking at the bigger picture of system-software maintenance and protection against data-theft. I would go for something like avast and malwarebytes in combination with a good firewall and systembackup strategy.
It's not bad to pay a bit of money but i don't like subscription fees. There is software you can buy that doesn't need a subscription or has a lifetime license and wil last you a long time:
- bootit bm (use it to make system-images, very good investment, os independant so extremely long lasting as wel, wil only get obsolete after drastic hardware developments, and you can use it on 3 computers for only 1 license i believe)
- outpost advanced firewall (a good firewall is essential and doesn't need signature updates for it's core tasks, this firewall comes actually with a lifetime license so although not that essential as with antivirus u'll be able to get updates and keep using it as long as the operating system stays supported)
- malwarebytes pro (lightweight one time fee protection, so usable as long as the os is supported as an on-demand malware-scanner that also includes realtime protection, but only in the payed pro version, so therefor i'd advice to go for the pro version already making the use of more heavy anti-virus a bit of an optional choice. also works wel in combination with other antivirus software)
Above software has no returning fees and wil already give very good protection, at different levels, which is the correct aproach: multi-level protection with at the basis good system backups, in the middle a good firewall and some light anti-malware, and at the end full fledged anti-virus.
Add for instance avast as a free antivirus. But there are other options. I would make a system-image with the firewall and for instance malware bytes already installed as a basic protection, and install a more full-fledged antivirus like avast last.
Anti-virus isn't more costly then other software but the signature database needs constant updating, meaning constant work, so that's why there are returning fees. Free antivirus is there mainly to lure you into buying the payed version, but using it as it is, is a cheap way to get some protection.
related (nested) answers on system-software maintenance:
https://answersrip.com/question/index?qid=20111125132022AAhaFxD
Note: antivirus has 3 main applications:
1: Detection. Detection is key. Once you know you'r infected you can take action. And if you have a good sytem backup and a good data backup then the response can be as simple as restoring those backups. You can use antivirus to detect viruses in 2 ways: using an on-demand scan or relying on it's realtime protection. But mostly only an on-demand scan wil detect an existing infection because realtime protection wil mostly prevent the infection and only point out dangers so no action would be needed. A good measure to take is to have a seperate bootable os dedicated to making on-demand scans because once your system is infected the antivirus may get compromised. Bootit bm wil allow you to set up multiple os-es so can be handy for this purpose.
2: Prevention. Using realtime protection is the main method of antivirus to prevent infection. This prevention can never be 100 percent effective though and can consist of heuristic scanning (looking for suspicious activities) ,signature scanning or innoculation (preventing files from being changed). Other preventive measures you can take yourself are:
- peridodical on-demand scans
- using common sense on the internet, especially when downloading stuff or executing on-site code.
(don't make the mistake of thinking you have antivirus so nothing can go wrong, there are scammers on the net and no antivirus can prevent you from falling into their traps if you don't pay attention, for instance do you know what physhing/spoofing is? If not you need to study more, knowledge is key also. For instance what do you do if your on a site that won't let you exit normally but displays a very attractive but somewhat non-standard looking exit-button? Answer: use the taskmanager to close your internet explorer.)
3: Repairing. In certain situations using the repair capabilities of antivirus may be the only, or easiest way to solve an infection. Another possible response would be restoring a clean backup, which may take a bit more effort, but is also typically much more reliable.