Amatitl�n or Atitl�n?
Lake Atitl�n is amazing. The view is simply unparalleled, and this comes from one who is familiar with pristine Caribbean shores and crisp Andean snows. The people are kind and welcoming, and one can find every comfort necessary.
Lake Amatitl�n, which is much closer to Guatemala City, on the other hand, has been fairly ruined by pollution. It's still worth the visit, but Lake Atitl�n in the Western Highlands is by far more spectacular.