Kaspersky is one of the most reliable and complete antivirus software. It also gives the user the possibility to take decisions during the scanning process, but doesn't stop to wait for user input at every detection as antivira does (or did when I used it); this is a good thing. I used to have avira, but every scansion was a pain, it asked for a decision at every single detection.

Though Kaspersky is a resource eater, especially when its update process starts. Thus, in the end, I think nod32, which is much faster, is the best, even though is a little bit less secure than kaspersky (or seems so; I never reversed them, so far).