My answer would be None/All of them.
You might not get infected with a poor anti-virus
You might even get infected with a good anti-virus.
Then there's another thing. .....Protection vs Usability
With higher protection you tend to be less productive/usability of the system decreases. You should find a balanced level of protection and usability, so that the anti-virus doesn't get in the way of your everyday tasks or doesn't delete files you need.
Keep the protection "Basic", any free anti-virus would suffice, and the rest is common-sense.
Exactly Jackuras.
This is good advice for the medium to expert user.
Any AV or similar program works like a second opinion on your good common sense... pick a sturdy security that doesn't slow you down. It could be something different like Panda and/or Zone Alarm, but as long as it works correctly and smooth on your system, its a fine choice.
Odds are good you wont get infected if you're medium to experienced user.
I voted Comodo, because its closest to getting a perfect defense (when tweaked correctly), its not too heavy, and usually is a good choice, with its AV and Firewall. Its the most effective alongside Qihoo and Avast, due to all being great on zero day and behaviour blocking. (with all 3 solutions tweaked from default settings)