I worked for Sprint/Nextel..
The Sanyo M1 gets better ratings from technicians than the other phone. http://reviews.cnet.com/Sanyo_M1/4505-6454_7-32177298.h...
The Samsung gets a higher rating from users than technicians. As a consumer, I would go with the Samsung.
Whatever you feel like... They both have pros and cons.
Feel free to pm me for more info!