I used to be a big Yogi until 5 years ago - many moves and two babies later -- I am planning on going back now that I am settled.
I think Yoga is better, but I also think you have to commit to it - you have to do several times a week, and really give it a few months, but then you will see and feel a HUGE difference.
The instructor can make all the difference too. I used to go to the 24 Hour Fitness Ultra Sport on my lunch hour everyday. But that was 5 years ago, so don't know if the same guy is there anymore.