I used to think it was the Gazelle EDGE with the shocks (which it still is!) but now I'm looking into the Jungle Gym XT suspension trainer (like the TRX only more durable).
P90X is great if you take it easy on yourself and don't push too hard. A person not used to exercise could REALLY hurt themselves trying some of that crazy Sh*t! LOL That makes sticking with it more difficult.
I'm also a complete worshipper of the Cindy Crawford workout video. The easiest way to lose weight is follow the 'Eat More, Weigh Less' nutritional guidelines. I have never failed to lose #20 when I followed that (when I NEEDED it, of course!).
Aside from the obvious answer of your fav activity!!!!!!........ I am interested to know your thoughts!