Resurrecting this thread to give an update.
I replaced Avast! by Kaspersky (courtesy of Barclays) a few days ago. So far quite happy, much less intrusive than Avast! And, assuming it's giving me much the same protection, then I'm likely to stay with it. Unless things change of course.
Happily running Windows 10 on both desktop and laptop
We have more and more laws, and less and less enforcement