I preferred the green, especially Georges Bayard's Michel series, about a 15-year old and his older brother who sleuthed like the Hardy Boys (Michel a Rome, Michel en plongee, Michel et Monsieur X, etc.) Except there were more kidnappings and last-minute rescues than the Hardy Boys faced, more stories set on boats and at the beach, and unlike the American adventure boy series of the 1940s and 1950s Hachette was not skimpy on the beefcake. He was as physique-intensive as the British boys annuals. Apparently being a teen sleuth gives you a magnificent physique.
Sabu, Jonny and Hadji, and Terry and Raji. But in the French translation, they both became teenagers in dhotis with beautifully drawn chests and shoulders.
Ebly also wrote the "Evades du temps" series (Time Runaways), about two teenagers, Thierry and Didier, who are hiking through a mysterious woods when they become unstuck in time, like Paul in Spellbinder. They meet the prehistoric teenager Kouroun, who doesn't own a shirt, and band together to fight supernatural enemies and look for a way home.
They even had gay-themed novels, such as Pierre Loti's Iceland Fisherman.
I wonder if my French teacher noticed that I only borrowed the books with the beefcake covers.
In college I discovered a whole new collection, the Signe de Piste.