I've been to many excellent small family run places where the owners/proprieters and staff know that you come out of your way for their food. They show their appreciation in many wonderful ways,and I appreciate their food. A few of my fav's are:
Aqui Es Texcoco, where Paco will gladly assist you with trying different things as well as accommodating your guests.
Marisco's Godoy, the whole staff is friendly and will help this gringo by explaining areas of their menu that I wish to try as well as cooking methods and spicing.
The Marisco's and Gorda trucks by the Toys R Us, always very friendly and patient to help with questions.
El Pescadore, the guys are just polite and friendly and willing to recommend a fish sammy.
I could list more but, this is why I will go out of my way to patronize places like this. Have places like this that are your go to places? What are your gems.