Hi Jen! For my classes, I don't have a company preference. I only look for really good mixes. I just got Radio Hits #19 by Dynamix for step class and that is pretty good.
As for video, that is a much tougher question. Legally there is no way to use top artisits hits whether they are redone by generic singers or not, unless you follow a very long process and apply through an agency. It is also quite costly per song making it very difficult to use for video. So for video music, the selections are not always what I want but I make the best of what is available or hire a composer to make original music (ie: Power Hour, Rhythmic Step, and the Slow/Heavy Series).