Martin Mystère! Basically X-Files before X-Files even existed. Incredibly well-researched series, always walking a tight rope between truth and fiction. The writer Alfredo Castelli is a living encyclopaedia of “strange tales” and esoteric lore. I’m not a fan of the comics (the actual stories are often too descriptive and verbose), but the topics it touches are fascinating.
Both Alan Ford and Martin Mysteré shaped me up. Alan Ford is extremely useful in business settings. They've described it all, business world operates on its principles. Martin Mysteré sparked a sense of wonder in me that never left. Italian comics were (are) the best!