I don't know if it's the best Mexican food in Cheyenne but I've always enjoyed Tortilla Factory on Central/South Greeley Hwy. Be warned their hot green chile is HOT! You can do half mild/half hot & it's pretty good. They'll also give you sample to see if you can tolerate it. Personally, I don't order anything with pork in it there, it's always on the dry side. Stay away from the Tortilla Factory by the mall, it's just not as good.
2706 S Greeley Hwy, Cheyenne, WY 82007