Avast: Free, with decent detection and some good features like deep screen and hardened mode.
Emsisoft: Very good detection, excellent Behaviour blocker. Not a lot of advanced features in my opinion, and because its user base is small, its cloud intelligence cannot match larger vendors. But it does its job very well.
Eset: Fastest malware response time, they can produce signatures for new threats within hours. Their generic signatures are excellent too, but it has poor zeroday protection unless you configure the HIPS well.
Kaspersky: Very good detection, excellent features. Its rootkit detection capabilities is very famous. But its malware response time is a little slow from my experience.
Norton: Excellent layered detection, behaviour blocker. Its file detection engine isn't the best though, because it is no longer focusing on static detection anymore.
360: Very good detection, its heuristics engine is very good too. Might be a little heavy and bloated.
Vote for ESET. ESET have improved alot since v.6 especiallly with it HIPS improvement (Smart Mode).
Very low false detection, low impact on most PC performance that i've seen, stable and much less buggy releases.
In real-world environment, protection wise ESET does the job quite well.