The spicer the better. Make sure to get the S1! I usually go for the P1 with the soft tendon, meatballs, tripe, lean brisket, and fatty brisket. Of all of the Pho restaurants that I have been to in Phoenix, I would say that this one is close to the top. Really accessable and easy to find and attached to a great international market. It has a laid back style to it and the waitstaff is very friendly.
A quick tip for any bowl of Pho that you get, order extra noodles on the side instead of another bowl if you are still hungry. It is a lot less expensive and gives you more to eat.