Not a fan of AVAST or BitDefender. AVAST is just packed with ads and full of bloatware if you get the internet security version. The virus protection is good, but I've heard its lacking as of late. BitDefender was very buggy in the few months I used it. As far as the protection is concerned, it does really well in tests. I've heard a lot of good things about Panda recently, particularly how it's becoming so light and its up-and-coming cloud protection. If I had to pick one, I'd go with Panda simply because of my bad experiences with the other two.
From the above 3 i would have to say BitDefender.
BD is the best choice in terms of protection, very good signatures, very good behavioral blocker and a nice firewall.
But if you have an old system like mine then you will notice slowdowns while browsing.
Fortunately never noticed any bug while i was using it.
Avast is my first choice, it has better protection and removal. On second place is BitDefender, good detection, AVC is very good (this gives BitDefender that good protection), the removal is not that good and has weak protection/detection against PUP/PUA. Panda is good, you need to be connected all the time for best protection, the removal is not that good.