The CTX and I series have different goals and are not that easy to compare.
CTX, "do-it-all-in-one-hour-a-day-endurance-workouts", features a variety of cardio styles in very intense and shorter bouts, but these workouts are certainly no walk in the park. They are some of Cathe's most fun routines, and two of these back to back form an awesome hour's cardio on a day when you really want to gun it. The weights work is endurance, but both the CTX upper body split and leaner Legs are great workouts, I do them a lot. They are both solid.
Having said that, the I series, a "shock-your-body" series, features Imax 2, which is a bit of a classic, a tough interval routine set to incredibly motivating music that you will be singing along to, when you can catch your breath! For me, the highlight of the series is, however, the pyramids: PUB and PLB. I do these more than any other weight training workouts and they are a blend of strength and endurance. I find I can go pretty heavy and also that the sheer number of reps completely exhausts the muscles. My upper body still hurts today after doing PUB this past Saturday! This series can help bust through plateaus, because you can max out for the last 8 reps with a higher weight and since you only have to maintain it for 8 reps, it may be enough to get you over the endge and intothe next poundage category.
I don't use the ME all that much, but it features some novel exercises and the good thing about it is, unlike PH and MIS, that the leg work is interspersed throughout the workout, so you are able to keep pushing on training the lower body throughout because you have not completely exhausted it with the first 10 minutes of the tape. I like PH still, but would do ME over MIS for this reason. ME also features some of Cathe's toughest core work around.
A lot of people love Bootcamp for an all round kick-in-the-butt total body workout: it has it all and needs working up to. It is also useful for its premixes. A lot of people do the cardio ony premix at the end of another cardio session for a "blast effect" at the end of the workout, and I do the "core only" premix a lot.
Cardio & Weights is useful for lighter days when you want to move and have fun, but not kill yourself.
Here's the low down, now you have to decide! It's not like you are ruling anything out: buy one now, one later! I think I might be tempted, in your place, to vote for the I series right now, because I think it might offer more variety of workout types and a variety of demands upon the body.
I can't rate Body Max for you: I have it, never do it after I got injured with it once, but others on here love it and swear by it. I think personally the beat is too fast for safe step work. PH is a tough and effective endurance total body workout with great music. I have never seen nor done Step max but it is an older and more basic Cathe choreography and I would personally avoid it for that reason, I think there's not much room to grow with it. IMAX is the original tough interval tape: some prefer it to Imax 2, it features most of the blasts done on the floor with very high impact moves, whereas Imax 2 incorporates the step throoughout and the music absolutely rocks!!! If you tend to get bored easily, shoot for Imax 2 first, because the intervals feature a combo of moves and more creative choreography, whereas with Imax, the interval features the same movement repeated for the whole minute/minute and half, and it can get boring.
Hope this helps,
Clare
