Here are some of my personal favorites. I have always been drawn to ones that work on developing a pretty six-pack, just so you know my bias. Also ones that are about 30 minutes long I usually like also.
Mark Blanchard - Power Yoga. He is a Yogi to many celebs. It is a grueling work-out and many of the poses are not accessible to beginners or to those that are not very flexible or have a lot of upper body strength. If you do this on a regular basis you will get that sculpted, toned look. I think it is 90 minutes. His language is very inspiring.
Ten Zen Tummy Toners - Rodney Yee and Cameron Shayne. These are actually two 25 minute workouts, that you can combine or do separately, I actually bought this because I am a Rodney Yee fan but have ended up doing the Cameron Shayne workout more only because my knees have been hurting lately and the Rodney Yee one was making my knees ache more.
Shiva Rea - Creative Core Abs. I love the music and drumming in this. Her language is very beautiful too. It's only 34 minutes. She does go a bit fast for beginners so this is probably better suited to at least intermediate level yogis.
Yin Yoga - Paul Grilley. Yin Yoga is a very meditative, slow, patient practice. You're not building up core strength in this kind of practice. He is great at explaining anatomy and the benefits a quieter practice. He offers lots of modifications as well. This is great value since you get 3 DVDs for a reasonable price.
Creative Yoga - Claire Diab. This is a great one for beginners and those with less flexibility. She does a great job os slowly and simply explaining the poses and offering modifications. She also has two segments on here that you can combine for a nice long juicy practice or a shorter one you can squeeze into your schedule. I used to do this one with my mom, who is not a regular yoga practitioner.