I think that the Crunch Joy of Yoga is an excellent beginner tape--it was my first about 2 years ago now. Karen Voigts Sculpt & Tone is more athletic, less "mystic," effective and solid tape. Yoga Zone has great beginner tapes, usually set outside in very pretty settings. Rodney Yee has a bunch of yoga tapes: "yoga for athletes" is one many people really love and is available at most stores that sell work out tapes. I saw it recently at Sports Authority. I don't really care for him as an instructor, but his workouts are solid.
My favorite yoga tape is Yoga Zone Power Yoga, but it is not the tape to start out with. I like Brian Kest too.
Know in advance that Yoga for strength is way different than Yoga for flexibility or Yoga for relaxation and you need to decide what your goal is with doing Yoga to pick the right tape. Go to
www.collagevideo.com and check out the yoga section. Even if you don't buy from them, their labeling system and description is usually pretty accurate (i.e is it mostly stretch, more power, chatty, eastern, beginner or advanced, etc.)
One final thought- If you get into Yoga seriously, invest in a good instruction book. You don't get the nuances of proper poses from a tape. I found my yoga practice has improved exponentially by combining a good instruction book with tapes.
Good luck!