There are several reviews of the 690 on the web page you linked to. Check them out. The 912's web page has no reviews, unfortunately. But looking at the case in the pics, it looks identical to my HAF 912 except for the black interior. Mine has grey. The reviews for the 912 Combat are sparse, but the regular HAF 912 is everywhere. You can easily read the reviews for it.
The 912 would be a bit better for air flow with the open area behind the front fan. Especially after removing the drive cage.
Also it takes a 200mm fan in the front, the 690 only a 140mm. My red lighted 200mm moves a lot of air a lot quieter than a smaller fan.
Appearance: I feel the HAF looks better than the 690, but beauty is in the eye of the beholder...