I have been at Certain Affinity for just shy of a year now. It is a veteran company that has been around for 15 years (with no layoffs, ever) but doesn't have all the red tape and bureaucracy of a... huge publisher. The executive team is very approachable and accommodating. They really care about the developers and understand that happy people make good games and good games make happy people. Certain Affinity has a storied history of assisting on some of the biggest AAA franchises including Halo, Call of Duty, Doom and Left 4 Dead. The company currently has some exciting projects and seems poised to make a splash in the industry within the next few years.
Certain Affinity is not well known in the industry due to the lack of publicity from its past focus on co-development work. This co-dev work has created a stable and respected company that is on the... verge of being a breakout company in the industry.