*pondering*
Sinfest has some pretty good days - and dilbert's definitely inspired...

... but XKCD is ... I think I like it better than both. Maybe it's just because it's written a lot closer to my own voice than the other two.
... maybe because while Sinfest's Glory moments rock - XKCD's are a lot more immersively personal and wildly hopeful - they could happen to me :)