No anti-virus is always going to find everything. New malware is released daily, and the scanners can only detect it if it knows it exists. It can sometimes take a bit from the time of release to the time scanners can detect. This means there is always going to be an "infectious" period. Most companies respond quickly, so the deciding factor becomes, "How much does it slow my system down?". For this reason I usually recommend Bitdefender, although some people have issues with it. I use Malware bytes and Super anti spyware just to run manual scans and they find most of the stuff. I also use roguekiller and emsisoft emergency kit if issues persist after using the other scanners. These run much slower, but can find a few extras the others might miss.
Long story short, Find a scanner you like for daily monitoring, and use as many as you can when doing manual scanning when you suspect you are infected.