Here's a thread that will give you some opinions.
And even more here!
The best way to go?
When using the word ''best''.. it will all boils down to what is best for you. There are those that feel best is, that which doesn't ''hog'' memory. There are those that feel AVG's ''price is right''. There are also those, such as I, that use McAfee and find it ''problem free'' - my criteria. Some people feel if their AV or anti-spyware hasn't found anything - it's ''no good''. Other's find if it picks up too many things .. they must be false positives. And the list goes on.
I understand your question, in that you were asking for opinions about AVG, since you have McAfee already. The above links should give you more than enough opinions. Maybe you'll get a feel for what is ''best'' for you!
Hope this was helpful..