For safety there is little difference. All the carriers have excellent safety records. There are complete carrier-by-carrier data available if you want to read them, but there are so few accidents it's a waste of time. South America is not central Africa and the carriers are all high quality for safety.

Soem prefer Lan, but that will make you go via SCL, which is far out of the way. TAM, a new *A member, is very good and has most of what you want. GOL/Varig does to. Aerolineas Argentinas has part, but not all, of what you need. Make you decision based on points, price, schedules or alliance, but don't worry about safety.