I used Kathy Smith's Power Step workout and Karen Voight's Energy Sprint for a long time. After doing those two for a while, I was ready for Cathe's stuff! I still do KS's Power Step when I'm not feeling like a 'speed demon' but still want to work hard (it's a slower tempo than Cathe's).
I also like KS's new Fat Burning Breakthrough workout for a short day or as an add-on to a cardio workout.
I admit, KV's ES is collecting dust now, but one workout I still use of KV's is Strong Arms & Abs. It's great for a day I want a shorter upper body workout, I usually use pretty heavy weights and go double tempo (more like Cathe's speed) for most exercises.
Absolutely any Christi Taylor step thing (and hi/lo as I hear) is just outstanding! Can't wait to try Still Steppin'!
I like to do Keli Robert's step tape, just for the fun of it. Sometimes I'll do that and then Body Pump ~ an evening with the Australians!
CIA 9905 with Franny Bendetto is one of my favorites!
Once in a while I'll enjoy doing Charlene Prickett's Step it All Off. I think it's one of her better step videos, and the scenery is wonderful!
And, like many have already said, CIA Power Bar Training is great! There's something they do that make my glutes so sore the next day!
Joyce Vedral's Bottom's Up ~ Upper Body workout is really effective too.
One thing I really like by Kari Anderson is Body Tech. It's kind of short but really efficient, great for a day when you don't have a lot of time.
Whew, I could really go on! Now I'm just getting all excited to do my workout after I get home from work today! Can't wait! :-jumpy