I used a Pentax K20d for a few years before I made the switch a Canon 7d. While the image quality at ISO 800 and below was excellent, Pentax's lens selection is lacking compared to Canon. After a few years of shooting with the Pentax system, I found that it just wasn't for me.
What you really need to consider is which system has lenses that better match the kind of pictures you want to take.
Something else you should really do, if you haven't already, is goto a local camera store and play around with both cameras. While one camera may be a better value, I'd personally say the Canon is, the ergonomics of a camera is something you cant get a feel for yourself until you use one in real life.