Where it all began! This book collects the first three years of Ben's (published) diary comics.
It's hard to explain what is so compelling about Snakepit. Ben himself admits that it's not particularly well drawn (he often calls himself out within particularly badly drawn panels), and more often than not the focus is on some boring aspect of his day...working, playing video games, etc. In these earlier years, there's quite a bit more partying, drinkin', druggin' and shenanigans than in his later domesticated years. But that's not the draw. It's something about the rhythm and flow from one day to the next.
Full disclosure: I'm old friends with Ben and published a couple Snakepit books (2009 and 2010-2012), so I can say with authority that you should be reading Snakepit (and on the toilet).