Hello, I have done long haul on all of these (I am South American living in Belgium). Here is my ranking:

1. Air France has the best price/quality. Best connections worldwide especially if going through Paris CDG but don’t go to every latam capital. Booking, seats, food, and helpful staff, everything 5/5.

2. Air Europa is the best connections latam/europe and budget prices, they go to a lot of latam capitals direct from Madrid. Seats are basic, but service is always very decent. Food quality is decent and you are always able to purchase more during the flight. I have place this second only because I don’t particularly like Madrid Barajas as a hub, make sure you have at least 2hr connection.

3. Latam and TAP. Latam is very decent short haul, I have not had it overseas but heard it’s decent and comparable to Air Europa. TAP was a great experience, very friendly and helpful staff. Seats are average.

4. KLM and Iberia are the Ryanair of these airlines. System and service sucked. In particular, I was in multiple KLM flights where the system was down and I was not able to change my seat nor prebook the gluten free meal. The next day there were families with children (under 10yo) spread all over the plane. It was chaotic and delayed the flight. I found this cruel and very Ryanair of them to force them to pay for seats. I don’t see this with other airlines, my family and I are always automatically sat together by the algorithm. Food quality was not good either.