Hola, you may want to go with one of the ones which places you with a family for a greater experience in language immersion. Choose also one of those that offers opportunities to get close to the Indigenous culture i.e. field trips, visits to marketplaces, ferias, etc. Look also for one which is not really in the “downtown” area of Xela but in one of the outlying neighborhoods/towns for also a more culturally enriched experience. Avoid the ones which appear to be one of many, language school chains or regional centers for others based in Guatemala city, Antigua or elswhere. If you have chosen Xela, you probably have a desire to experience not only language but culture as well and therefore will do just fine linguistically through the experience rather than paying for the big name schools. Know what I mean? Buena Suerte!