[Quote]Yoga is awesome.  The best exercise around.[Quote]

Awesome, yes it is.
Best Exercise, that depends on what your looking for in a workout program?

Flexibility/ muscle tone/ increased lung capacity/ overall body health, yes to them all.

However if your into a sport that requires long term muscle endurance like cycling/rowing/ cross country asking etc, it will help on your off training days but it won't get you in shape for those activities.
The best exercise for you sport(s) is actually doing that activity. If you can't do the activity you want a workout or exercise machine that can mimic the muscles used and body movements as closely as possible.

The best workout regime is one that combines the Big 3, Cardio/ Resistance work/Flexibility.
You can emphasis one or more for the specific needs of your given activity, but there all important and far to often one or more are overlooked.

Even the best exercise machines have there limitations.
Rowing is a great exercise but it does have a drawback?
Like cycling, rowing doesn't put a load on the skeletal system.
Not an issue until you swing that heavy portage pack/canoe/backpack and head off down the trail.
Cross training is the key. Find cardio/resistance workouts that mimic as close to possible the muscles/movements( if possible) of your chosen activities and you'll be on your way.