We live just a bit south of that area on Grand Parkway in Richmond (just a bit south on 99 from 1093 which goes out to Fulshear). We like Pablos, Lopez and Las Mananitas. All of these are at Grand Parkway and Mason roughly. Lopez is the closer (more northern) location wise.
Pablos - Very good margaritas, including special recipes. Nice atmosphere and with a good bar. Food is good (some people swear by it). The wife likes their fish tacos.
Lopez - Been going to Lopez (at another location) since 1976. Very good margaritas. Good atmosphere and a nice bar. Good to watch a game (Lopez family love the Astros). Location is attached to the Gallery Furniture store. Menu is a bit limited but their enchiladas are the big hitter. Fajitas are ok.
Las Mananitas - We like the margaritas (on the rocks with Patron) but they don't have the specialty margaritas. This place is a bit more of the traditional Mexican joint and more simple. But we like the food a lot including the fajitas, enchiladas and other stuff. Large menu.