Detailed malware detection test results are regularly posted here for nearly 2 dozen products, free and paid:
These are very detailed, showing EXACTLY by name for each malware/virus if it is detected or not, for each product, then products are ranked 95%, 85%, 75% etc based on detection rates. Historical results are maintained so you can compare over time, and you do see product results change with each test (done every month to every 3 months depending on whether there are any new reported malware in the field, and a sample can be obtained for testing).
I've done a bit of research on the site and tester, to make sure it was not one of those 'sponsored' sites by a vendor that are made to appear as objective, neutral reviews. The fact that the product rankings change constantly AND that the results are very specific and listed in detail, further support that this site and the tester are very objective. In fact this is exactly the kind of site and test results, that vendors DON'T want you to see, even the ones that do well on the test (because no product is 100%).
I am posting this to support the Mac Community. When we are all better informed when it comes to this important area of security in this day of cyber threats, we all benefit. Education and information is the best defense, (as with so many things in life). For example, if someone uses MacKeeper because they don't know better, then in some ways the community failed for not getting the word out. If after doing some research and being advised not to use MacKeeper, someone still chooses to do so, then you can't help that, but hopefully it wasn't because there wasn't information available.
My aim is not to support or dissuade anyone about a particular product, you pick / use or don't use whatever product you want, and live with the consequences, just remember that your decision can effect others, by virtue of whether you are part of stopping the spread, or being a part of it.
I highly recommend you don't just look at the current results, but look at the past ones as well. You WILL see trends, with some products consistently doing well and others not so much, and some moving up and down. Remember, an A/V product rests on two main things, the scanning engine AND the malware database. A great engine can be crippled if the database is not updated in a timely manner. Conversely, a vendor that does maintain a current database might still not be effective if the program itself is buggy. This site only ONLY addresses virus detection results, it does not in general make any conclusions or post results regarding performance, installation, support, UI, etc.