Iyengar yoga is the best kind of yoga out there. Iyengar yoga instructors are the best teachers of yoga (in the west) because they focus on precision and technique. Most of what people call "yoga" is total BS.
I wouldn’t call Iyengar the best. Yoga has certainly shown me how different bodies/minds respond, engage with, like different aspects of yoga. And anecdotally, the teachers I liked most have hatha backgrounds
Personally I think yoga is a form of blood magic. Beyond that, it has a religious (Hindu) slant to it that I believe most completely gloss over. Also I’m pretty sure every culture has stretches, normally it’s just something you do on your own and go about your day.