That's a great question for anyone dealing with city living! The constant battle against rain getting into your outdoor bin is real—it creates mess, odors, and attracts pests. From my experience, the best lid is one that creates a solid seal and sheds water quickly.
For maximum rain protection, a domed or rounded lid is the top contender. Its sloped design doesn't allow water to pool; rain simply runs right off. Pair this with a tight-sealing hinge or a gasket, and you have a near-fortress against the weather. Many heavy-duty municipal bins use this design for a reason.
A close second is a well-fitted, hinged lid that sits snugly on the rim. The key here is the quality of the hinge and the lip. It should close firmly and not warp easily. Avoid flat lids if you can, as they tend to collect puddles which eventually find a way in.
For simpler bins, a snap-on or lockable lid can work well if it has a deep groove that securely fits over the bin's top edge. This creates a good overlap that deflects light to moderate rain.
Ultimately, look for durability, a sloped shape, and a tight seal. A good lid keeps your trash dry, minimizes smells, and makes collection day much less unpleasant for everyone on your block