I currently have a KK RM. It's a good workout. Be aware though....trainers are boring as hell. I find that about 45 minutes on it is my max.
If you are like me, you might want to consider one of the electronic trainers on the market. Performance Bike sells 2 or 3 under the Axiom name I believe. These hook up to your computer and you can watch videos that match the resistance you feel. The resistance changes with the "terrain" on the video and you can buy other videos to vary your workouts. I had one of the mid level for about 6 years before it finally gave out. The price aint cheap, but I am thinking about getting one again. Makes for a much more entertaining hour or more on the bike when you can't ride outdoors.