This was the community I first got involved with when I first landed in México. Expect to see a mix of foreigners and locals. Friendly and open vibes everywhere.
ISM has bachata, salsa, and Cuban salsa classes literally every day for beg/int dancers. They also have boot camps to level up with the same group at a higher intensity.
They usually host their classes at Marketeatro (Coahuila 105, Roma Nte., Cuauhtémoc, 06700 Ciudad de México, CDMX).