As someone who likes to dine out fairly regularly (mostly in the Nassau County area), I'd thought it would be good to point out the top restaurants by cuisine, in my opinion. This post is focused on Mexican, but will be doing others revolving around Italian, Chinese, etc.
10. Three Amigos Mexican Grill
Overview: What's good about this place is not only the food (which is excellent), but has something for non-Mexican lovers as well (i.e. salads, mozzarella sticks). Tacos are about the same price as Taco Bell's and much fresher (and better).
Favorite Dish: South West Burrito
9. Little Mexico
Overview: The name matches the size of the place. Very tiny, but place packs a lot of flavor. Definitely more of a takeout joint, but worth it if you're in the area. Also extremely inexpensive and has dishes you can't find elsewhere (i.e. beef tongue sopes and tortas)
Favorite Dish: Sopes De Lengua (beef tongue sopes)
8. Don Juan
Location: Massapequa Park
Overview: One of the more well known places on the list, Don Juan provides consistently good Mexican food (and drinks) at fairly inexpensive prices. A lot of people will list this as their favorite (mostly due to them not trying others on the list). While I don't agree that it's the best, it certainly is worthy of top 10.
Favorite Dish: Don Juan's Especial
7. On the Border
Overview: On the Border is not only a great place for Mexican food and drinks, but one of the better Mexican joints to go to for Cinco De Mayo. I'm not usually a fan of putting a big chain on a list (hence why no Chipotle), but On the Border is good enough to make the top 10.
Favorite Dish: La Bandera
6. Aztec Emperor
Overview: I love how this place is fairly unknown compared to others on the list (means less of a wait for me :) ). This place has the best salsa I've ever had making the chips and salsa they serve worth the trip alone.
Favorite Dish: Mole Poblano
5. Laguna Grille
Overview: This place is always packed - and with good reason. Laguna Grille serves up above average Mexican food that's constantly great. They also not only give you salsa and chips before the meal, but plantain chips as well (a very nice touch). Laguna Grille is my pick for best steak fajitas on Long Island
Favorite Dish: Steak Fajitas
Overview: Great place to visit during the summer as Cozymel's offers an outside patio. Regardless, if you enjoy Mexican food you'll enjoy the food at Cozymel's. The place also makes one of the best margharita's you can get on the island.
Favorite Dish: Homemade Tamales
Overview: Casual, but still a good place to take a date to. Mangoes serves up great Mexican food at fairly decent prices. A big plus about the place is the Mariachi band that plays on Fridays and Saturdays. Definitely something you don't want to miss. Even if you come here on another day, the food alone will make it worth the trip.
Favorite Dish: Lobster Quesedilla
2. Zim Zari
Location: Massapequa Park
Overview: Not a fancy place by any means. This place reminds you of an eatery you'd see right off of the beach - including the surfboard shaped menus. The place boasts one of the best meal deals on Long Island with "taco Tuesday" which are $2 prices for their signature tacos. There tacos are the reason to come here ranging from their take on a surf and turf to tuna tacos and more. Taco lovers will not be disappointed.
Favorite Dish: Surf & Turf Tacos
Overview: Besito is not only the best Mexican restaurant in Nassau County, but probably one of the best restaurants on Long Island (tied with Waterzooi as my favorite). It's upscale, not cheap whatsoever, but well worth the price. They have the best table side guacamole I've ever had and everything I've gotten there was beyond delicious. Plus, they have an amble amount of tequila and other alcohol. A+ all around.
Favorite Dish: Tie between the Costillas Al Piquin (short ribs) and Budin De Mariscos (shrimp and crab pie)