I don't like AVG. I installed it once, gosh, it was the WORST experience I have ever had. Let in loads of viruses, and the ironic thing is it wouldn't delete them!
Tried Kaspersky, and boy, that is one heck of an AV. Wonderful detection, real-time defense, quarentining and deleting is a breeze, really, you can't go wrong with that. But it's paid, though.
Never tried NOD32, but I'd go for it first than AVG.
Personal opinion.