It has been a while that I have used KL on the route between EZE and SCL. However, I can remember that even on this short sector, they were handing out the famous ceramic Dutch houses filled with genever. Not sure, if that has been a victim of cost cutting in the meantime.
As for LA, they have only recently restored wide-body flights between SCL and EZE (one per day). So over the last years, this route only saw Y+. Service usually consists of a cold meal (e.g. salad with chicken) and a dessert together with a full bar service. However, it could also happen that you may get one of the ubiquitous „gourmet“ sandwiches…
As for the hardware, probably KL has the nicer product and for sure Dutch crews are among the most uncomplicated and approachable people, also thanks to their good language skills.
This is a point that I would definitely consider with regards to your question, if there are differences between Chilean and Brazilian crews. In my opinion, Chileans outpace Brazilians in friendliness and professionalism. While many prefer speaking Spanish, Chileans always make an effort to communicate, whereas I have noticed that many Brazilians continue in Portuguese or go in complete mude mode even when they realise that a passenger is not fluent or does not speak Portuguese at all. That is an attitude that I find somewhat annoying (coming from someone who is fluent in Portuguese, although I have the wrong, i.e. European, accent).
Another aspect is that Chilean pilots (currently on strike and sabotaging my travels) are very well-trained to cope with the sometimes rough and unpredictable weather conditions, especially over the Andes. I always feel safe when flying on Chilean LA.
Last but not least, I was surprised to see that a 777 was assigned to your GRU - SCL flight. I have not seen that in ages. If I am not wrong, all flights between SCL and GRU (and vice versa) are currently on LA Chile metal and that means either A 320 / 321 or (once or twice per day) a 787.
Before the merger, JJ used to fly 777s a lot on that route, but now they are rather used for the intercontinental flights out of GRU.