I use Windows inbuilt av but every computer is running a paid version of Malwarebytes. MBAM has 4 protection modules: web, exploit, malware and ransomware. I was lucky to have purchased 5 lifetime licenses so I don't have a yearly fee to use the program.
You could use the inbuilt free av and MBAM free. (when you download it, there is a trial of the paid version; after 7 - 14 days, it reverts to the free version). Just be sure to scan with MBAM once a week.
Well, sadly you didn't tell us what OS you are using.
If Windows 7, I recommend Microsoft Security Essentials (MSE). If W8.1 or W10, I recommend Windows Defender. You have to download and install MSE with W7, but Windows Defender is already built into Windows 8.1 and W10. Once you uninstall ESET, Windows Defender (WD) should automatically enable itself.
Don't let anyone tell you (WD) is not good enough. It is plenty good as long as you keep Windows and your security current - the same thing you must do anyway. And you need to avoid being "click-happy" on unsolicited downloads, attachments, popups, and links - again the same thing you must do regardless your security of choice.
And last, and again regardless your primary scanner of choice, you should always have a secondary scanner on hand for on-demand scanning just to make sure you (the user and always weakest link in security) or your primary scanner did not let something slip by. I recommend Malwarebytes for that.