I'm struggling to think of anything that could serve as a better source, or even a reasonable runner-up. Am I taking a broader interpretation of "news"? I would agree that cable news is probably a net negative; web aggregators like Google are hazardous, and following individually-selected news sites is a lot of work, but what else is there?

You can look at their voting record, or who they take money from. There a number of "non-news" websites that have this information.

Yes the important stuff is public record, but it's also hard to analyze the primary sources. Bills tend to have misleading names, mixed content, and non-obvious agendas. Context is important; it's not uncommon for someone to oppose a weak bill because politically the alternative is a stronger one, not inaction. The FEC database is hideously formatted anomaly-filled MS Access stuff. I generally let someone else do the analysis, but then that's "news" (or at least subject to the same pitfalls?).