Which smartphone is better? The HTC Desire or the Samsung Galaxy S?

I have US Cellular, and I'm upgrading to a smartphone soon. I was planning on getting the HTC Desire, but US Cellular is getting a version of the Galaxy S later this month - the Mesmerize.

Which is a better phone?
The iPhone isn't an option for me... plus, I really dislike AT&T...

I'm sticking with US Cellular and getting either the Galaxy or the Desire