That's a fantastic question that touches on both practicality and design! The eternal struggle between being noticeable enough to be used and not becoming a visual blight on the landscape.
From my experience in urban planning discussions, the consensus often lands on a few key colors that strike this balance. Sage Green or Forest Green is a top contender. It's a natural, calming color that blends well with parks and streetscapes, yet it's distinct enough from most backgrounds to be seen. Many European cities use this shade effectively.
For higher visibility needs, especially for recycling or specific waste streams, a Deep, Earthy Orange or Terracotta works wonders. It's bright and eye-catching without being as harsh as pure neon. It signals "action" or "caution" in a warm, inviting way.
Don't underestimate Charcoal Gray or Dark Slate. It looks modern, sleek, and hides dirt well, while its dark tone still creates a clear silhouette against lighter pavements. Pairing it with a brightly colored lid or signage (like a vibrant yellow for recycling) gives you the best of both worlds.
The real secret often isn't a single color, but strategic two-tone combinations. A dark body (navy, dark green) with a bright, contrasting lid (yellow, lime green) draws the eye directly to the opening. This is psychologically effective and looks intentionally designed.
Ultimately, the "best" color depends on its environment. A bin in a historic square demands a different palette than one on a modern university campus. The goal is to choose a hue that is *contextually visible*—it stands out just enough from its immediate surroundings to be found, while harmonizing with the broader aesthetic. It’s less about shouting for attention and more about being a helpful, integrated part of the public space.