I’ve just bought myself a GoPro HD.
Did a fair bit of research, and it was always between the Contour HD and the GoPro. At the end of the day, i’m more concerned with the quality of the footage rather than how it looks on, and the two were very comparable.
However, the variety of mounting systems, the extra functions (still shots, timed shots etc.) and, ultimately, the price, all pushed me towards the GoPro.
Both cameras deliver excellent footage, from what I’ve seen, so it really is up to how much you can spend. Those are certainly the two to choose between though!
Oh, and as a lot of the video hosting sites compress the footage, over on Vimeo you can download the raw footage for a better view of the quality. HTH