I don't think it matters all that much. There are several good ones. I use Giganews, but that's only really because their deal seemed to be the best at the time I signed up. Easynews is what my brother uses, and he's quite happy there. I think Easynews has a web interface that you can use to make downloads easier, but I've never really looked into it. Any of these commercial servers will probably give you all the Usenet you need for something like $10 to $15US per month. For me (and, I'd submit, for any dedicated archivist), that's well worth it.