I have tried all the above, but always come back to AVG... works great on all my various PCs and laptops.. and on all the different OS they all run.
I love AVG! Its the only one I'll use anymore. I've tried Norton, it came pre-installed on a computer a few years ago, & it let several viruses through!!! I even got my sister-in-law started using it because she needed one to replace the pre-installed anti-virus that was expiring.
I'm using Comodo Internet Security for the time being and I'm quite satisfied. I have used Nod32 in the past also a great av, but I don't want to buy a license every year.
There is no reason to be paying for Anti Virus these days when the free ones are so good.. and in some cases better!