Coming from San Diego, I am very familiar with Rubio's. Consistent quality and the best fish tacos from a chain.
They now have mango quacomole which is essentially regular guacomole with a topping of mango salsa. The salsa is very good and they will give you some on the side without the guac if you ask (for a small fee of course).
I love the fish tacos and the carne asada burrito.
Because it is a chain, you don't have the diverse menu choices the more authentic mexican restaurants do but you get good quality.
I am only disappointed with their specials like lobster burrito that come and go. They lack the proper flavors and when you like something, it disappears for a long time.
Still, for consistent quality and flavor, Rubio's delivers.