i've tried several AV/IS software. started with Norton several years ago, very slow for my old PC.

after that, i moved to bitdefender. it was great for me initially but started to behave like norton.

now, i'm using kaspersky IS. didnt buy it coz of promotion/publicity, but based on reviews and bcoz i want to try it. KIS works great for me. block/detects all threats. besides, its cheaper compared to other non-free solutions. i bought 3-licence version, 2 for me, 1 for nephew.

thats my personal experience.