every antivirus software is best software to cleanup computer viruses, but the condition is that it should be updated.in my pc i use kaspersky antivirus.because it has many utilities in it and is powerful virus remover.and also it does not slow down the computer as other anti virus software do.
You'll must not have tried Stopzilla yet. Compare it to any package sold on computer shelves or sites and it is far superior. And it has kept evolving adding additional capabilities with newer free versions after you obtain the original version. I've had it for over 10 years now and have seen it evolve into a giant for profit company.
Mostly, all the free ones don't work as much as ones that you buy. But, I recommend you buy Norton. It helps clean up your computer really well and keeps the computer virus and tells you if the sites are good or bad. Hope I could help.
In some cases, destructive viruses can damage some system files like registry keys which are much important for the smooth running of the whole system. Hence I highly advise you to use a useful tool to scan the OS and repair corrupted system files. If you are stuck with any computer virus, you can go to pccaretips.com/blog/ to get effective removal guide.