Helena's place is one of the best in CDMX: it's located in a secure apartment complex with friendly staff, great facilities (the gym and rooftop are amazing), the neighborhood offers great cafés, restaurants, and parks, and you are a few minutes walk from several supermarkets and the metro.
Helena is a great host, who takes time to ensure your stay is up to your expectations. Everything you need for a long- or short-term stay is in the apartment. You won't be disappointed here.