Sluggy Freelance

Admittedly, I'm not an expert on webcomics. In fact, the only ones I read with any faithfulness are xkcd, sluggy, and VGCats. The first updates on Mondays, Wendesdays, and Fridays, and the last updates not at all. Sluggy Freelance updates daily, and has an incredible story. It's a little hard for new readers to jump into, given that it has been running for more than ten years, but it's well worth reading once it picks up, and it only takes around a week of afternoons to catch up. If you're still not convinced, just take a look at this:

Sluggy Freelance: That Which Redeems