Honestly, if you've made it to LATAM's local website, you're probably not going to ever be buying their gringo fares. So LATAM is being pretty foolish hassling folks.

I guess if you think they'll hassle you at the airport, just buy from Sky. My Chilean domestic flights on LATAM last month were pretty crummy. They're at 29" inch pitch (but they still allow seat recline -- ouch!) and they no longer give you free drinks and snacks. And one flight was an hour late. I flew Sky a couple months ago: my flight from SCL to Mendoza was short and not memorable, but I don't think it was worse than flying LATAM. As a low level AA elite, I did earn about 300 AA miles for each of my deeply discounted domestic LATAM flights (worth about US$3), but I don't think that will tip my buying decisions very much.

It does seem like Sky has slightly more limited carry-on baggage rules (I don't know if they enforce them), which might be my only REAL reason to prefer LATAM.