Hey Daniel, actually I collect from all airlines of all world and from any era. As well, I collect different kind of safeties from de same airline/aircraft, for example, I have two Swiss A320 safety card with different codes, one is 0612-13-16653, the other is 1008-13-16654, it’s just revised versions of the same card, with tiny differences.
So, I allways ask for my friends to bring the SC when they took a flight, despite I have that card or not, as well, from 6 to 6 months I ask for airlines to kindly sent me an SC, some of them really send (I can list the airlines that sent me at least one time if anyone want to know).
But, of course I have some focus for the collection. I priorize phased out aircrafts, or aging. African airlines, russian airliners in general and airlines from “different countries” are allways nice. And as a brazillian I like to collect the airlines of Brazil too.