Hi sibin,
I use SQLyog and DbVisualizer both for 5 years or more and there is copy/paste, excel style, feature in DbVisualizer that is very handy in data manipulation. I think that feature is essential for QA work and cratering data fast and efficiently. As you have copy selected rows (csv format) there should be paste data, multiple rows possibility. You can see how well this feature works in DbVisualizer. In the other hand SQLyog has excellent copy tables to other server feature that DbVisualizer do not have. That is my destiny, I have to use it both tools.
Regards,
Vojin