S.K.
I really like Debbie Siebers workouts. YOu can buy that at www.beachbody.com. Unfortunately, they are an hour long so I have a hard time completing them now but I swear they kicked my butt.
I personally, am not a fan of Denise Austin. Even on mute she annoyed me so I would say try to rent one before buying it because I know some people love her and some do not.
I too am considering buy Tony Horton's 10 minute trainer as I like the idea of a shorter work out. I know people who have used his other stuff and liked it so I can't see this being any different. Good luck.