Rubios is the holy grail of Mexican fast food chain restaurants. It is a bit expensive and the portions are a tad bit small but there is quite simply nothing that compares for this type of restaurant in fast food. Now, it is definitely not authentic, but if you know that going in, you won't be disappointed.
Also, let me be clear, there are a ton of better Mexican restaurants in Phoenix but this is a place you can count on to fill your craving every time. It is the best Mexican FAST FOOD out there. I constantly crave the fish tacos and drool over the baha grill burittos. If you want quick fast food with a Mexican flavor, this is a great choice. The staff are very friendly at this location as well.