A good thing to do to help form an opinion is go to places where some tests have been done. AV-Comparatives
is a popular one:
For an overall picture of the tests done there, click on the link that says 'Whole Product Dynamic "Real World" Test' and then the 'Monthly Results' link for a graph.
Click on the 'VB100' button at the top of the page and choose 'latest comparative' to see their graph (click to zoom).
Results vary from place to place and from month to month but the sites can help you to decide on what to switch to.