Being from California I am always on the search for the best mexican food in New York. All the mediocre expensive places make me so upset and while I love Cosme, you just can't eat there all the time. Los Mariscos has great fresh seafood, amazing authenticity in tortillas and some options, and a flavor of Mexico that's missing from so many NYC Mexican establishments.
The Agua Frescas are all so good, but no matter the time of day, I'd definitely suggest a mezcal margarita! Great option.
The special spicy shrimp taco is my favorite, and I know it's not authentic, but it's soooooo goood. The aguachiles are very solid, but I think the ceviche gives you better bang for your buck.
Make sure to try the homemade salsas! They are definitely soome of the best homemade salsas in all of Manhattan.
This really is a great place to go...it's not fancy, it's not tooo cheap...but it's a good middle ground with great seafood and excellent execution and flavors.