America's Taco Shop is definitely one of the best taco shops in Tempe. As an avid Mexican food consumer, I would highly recommend America's as one of the best, most authentic taco shops in town.
In terms of food, I would personally recommend getting the Al Pastor. The pork and pineapple blend is out of this world. Their guacamole is also incredibly fresh and worth the price.
Literally the only reasons why I don't give this place 5 stars is because I wish it had more available seating during the day. I also think they should be open 24/7 but that's just me!
Also, if you work in the area and want to throw an awesome work party or something, place your order online. It will save you lots of hassle.