I suggest sticking with NOD32.
If you do decide to use one of the free ones I also suggest running a monthly scan with the free version of malwarebytes and the free NOD32 online scan tool as a backup. The free versions of both don't let you schedule it so you have to do it manually.
Personally I just use the two of them and windows inbuilt Defender and it works for me, a bit of care in how you use the PC is also a great help. If you want to have something that just works in the background though you are better off with one of the paid solutions and NOD32 is a very good one.