Honestly I used to say that MSE was the best until recently it started doing poorly in recent security tests and so I tried out COMODO Internet Security due to people saying how effective it is, and how it scores good on tests. My experience so far has turned out to be excellent and it even found a bunch of stuff that MSE missed, though the only false positive COMODO has detected so far was The Witcher trainer.
If you do try out COMODO I recommend setting the firewall and defence+ in training mode so it can learn how you allow your system to behave. Though if you know what you're doing you won't need to set them in training mode. And COMODO also comes with a game mode so it won't bug you when you're playing games.
Norton and McAfee are cool, but they use a lot of memory. So forget about them. Nod 32 is good too, but one of my friends said it deletes trainer when downloading is done, even the AV is turned off. So use Avira or Avast or microsoft's stuff instead.