I've had Mac products for years and never had a security problem. I'm just wondering how many people who own Mac products are now putting anti-virus software on their computers. If so which one is the best.
Please do a search for your antivirus questions on this site.
There's several (dozens, perhaps hundreds) existing threads that discuss a variety of antivirus products, or even the need for such products on OS X. You will even see links to other similar threads on this page when you scroll to the bottom of the posts.
That being said - If you have never had a security problem, that's unlikely to change, whether you install AV software or not.
Just my opinion, the "protection" that you might get from AV software is not worth the performance hit from using it full-time.