AVG is better in heuristics, it uses less memory and performs fast. Kaspersky is better in detection, it is slower since it scans thoroughly and better. Most people use AVG, being a freeware. but if you're on quality and not on expenses go for KAV. Some viruses can be detected and removed by AVG and not by KAV and vice versa. One is better in different categories. but so far as i have tested, KAV is better. But if you want, you can have/install both but use KAV as your main. AVIRA also good one.