What is a good newsreader?

What makes a good newsreader?

It can thread articles
Defaults to plain text posting and viewing
Good filtering options
Allows batch downloading for offline reading and replying.
Trims signatures
Encourages interleaving comments and snipping out irrelevant quotage.
Built-in common sense, like preventing cross-posting to a large number of groups.
Allows weighting of posts, so that more useful contributors postings stand out.
Allows a post to be kept indefinitely (build your own knowledge base!).
Intelligent downloading of posts - ignore attachments or posts over a certain size.
Marks as read a crossposted article that you've read from another group.