If you like Intensity series, you will really enjoy it and it's sweat inducing plyo combo (& just variety) of these! I do not like the step choreography in Imax 2, so it isn't for me.
I cannot remember the other two, but I thought Viper was pretty good & definitely for an advanced (at least cardio wise) exerciser. I hope a Cathlete who has a better handle on her 'older' step routines can be a little more specific for you! lol. For me, many of them are not doable and take up way too much space. I admire the talent and execution behind all of them.