Microsoft Security Essentials (or Windows Defender in Windows 8, they keep changing the name) has one of the lowest detection rates you'll find, about 90%, because they don't want to have false positives. They do well in that regard, they are pretty much 0 false positive all the time, but it is a tradeoff in detection. Good for regular users though since many non-technical people get pissed at false positives.
If you are willing to spend money, I recommend ESET NOD32. It's detection rate is good, and it is quite fast. You can also set it to exclude extensions like WAV, NKI, NKM, etc to it doesn't mess with audio software.
For the highest detection rates, look at Kaspersky. Still not 100%, but tends to be the highest out there. Trend Micro also tends to be good but is really slow.