When I look at the unsold listings, I see that the agents live in different cities across Texas as well as from across town. This is a disservice to the seller. The local agents know about the areas that flood, trends in the area, schools, how to price a home in their familiar area, and area activities. No one can know the entire city. Houston is the same size as Rhode Island.
Local agents all know each other, know the area, trends, schools, and how to price a home accurately. If you don't know an agent, you could look at the subdivision newsletter. Those agents work their area and are the experts. They attend open houses, they have made a huge financial commitment to advertise, and are available for sign calls. If I got a call to see a house in my neighborhood I could be there in a matter of minutes. If I got a call where it took me an hour to get to the house to show it, I would be less likely to show it.
To sum it up, choose a local realtor! Your house will be priced correctly, buyers can call to see it with short notice, you will know which areas are track homes, production homes, or custom homes when pricing, you will know the neighborhood deed restrictions and amenities of the neighborhood.