I have an elliptical, too, and I prefer the Cardio Coach workouts.
I have 4 iClimb workouts; 1, 6, 14, and 17. They're okay but IMO they don't compare to Cardio Coach. Yes, they are cheaper, and they should be because not as much goes into them. I will try my best to compare and contrast them for you.
Music:
iTrain - I don't know the source of their music, and I couldn't find anything about it on the website. It's not terribly memorable.
Cardio Coach - each workout is scored by Todd Washburn with original music, in much the same way a movie is scored. It enhances the workouts and is perfectly suited to them.
Coaching:
iTrain - Keith and Buddy (iClimb and iCycle workouts) know their stuff and you will get a good workout if you are motivated to do so. My problem, and this is just my opinion, is that I don't find them terribly motivating. They kind of bore me, and I find myself just wanting the workout to be over.
Cardio Coach - The time absolutely flies by during a CC workout. Sean O'Malley is known for his motivational skills -- it's his trademark. He really helps you to focus mentally on the task at hand, so much so that you kind of don't realize he's trying to kill you.
Think of it like this -- Cardio Coach is to mp3 workouts what Cathe is to DVD workouts. They're both picky and tend to the smallest of details. They're trend setters in their particular areas of expertise, and everyone else is trying to be like them.