I'm in the process of booking an itinerary from IAD to UIO. As it turns out, I conveniently have three options that work out for my schedule: Avianca via. Bogota; TACA via. San Salvador; or Copa via. Panama City.

I am a United Premier Gold / Star Gold, and have never flown any of those three airlines or to any of those three hubs before. Which of those provides a better onboard product / better transfer airports? Are there any that I should avoid?