Don't forget that *both* locations are run by San Angel. I was very when La Hacienda opened in 2010 that it inspired their cousin across the walkway to improve their service, after several years of less-than-stellar reviews.
Personally, La Hacienda has been my favorite Epcot restaurant since it opened, both for service and food. I just wish the menu was a bit longer. Esmeralda has become my "personal server", even if I'm only there about once a year. (Somehow she always remembers not just what I ordered, but which table I was at on my last visit.)