1 stop or non stop flights

We used to fly United through Houston, but after the merger, they seemed to have changed the schedule often requiring an overnight. Needless to say, we don't do that anymore. Now we fly Delta to Mexico City and then on to Zihua. We love the new(ish) terminal in DF, which makes connecting very easy. Also, customs is way more efficient than in Zihua. (Delta had a direct from Atlanta for only a short time a number of years ago, but they cancelled it before folks even realized that was an option.)