Having zero affiliation with any SLR manufacturer (and even in PnS land I was only a Kodak / Fujifilm guy), here are the reasons for my K200D purchase:
1) Good high ISO performance
2) Lens compatibility
3) Weather sealing
4) In-body SR. Saves lens money
and makes any lens SR!
5) Reasonably good kit lens (I didn't have cash to buy another lens)
6) AA usage, a plus for me.
7) Very high build quality.
8) Not a 4/3 like Olympus
Things I would change:
1) Faster burst and larger buffer
2) ISO 3200
3) Better viewfinder.
That's really it....It's a lovely camera.
Remember, it's what someone told me on another forum I visit.
You're buying into a
system. Accessories, lenses, etc. The body is really a small part of the overall equation, as they change with the times. Lenses are for a lifetime (usually)!
Look at the ranges you want to shoot, look at the prices of the various 1st and 3rd party offerings and go from there.
Unless the body has a serious shortcoming (Nikon 40D, etc) then the body isn't as important as the lens ecosystem, IMO.
Even still, love my K200D! I've briefly considered the K20D upgrade, but nahh...maybe next revision