The best overall cap has a conical liner to help it seat into the bottle neck. This type cap can be washed thoroughly and used over and over again. A flat plastic liner would be the second choice. A cap with a cardboard liner should only be used once as it may absorb some of the solution. A metal foil lined cap should never be used.
If the green caps are made of hard plastic then there should be little difference between them and the conventional black bakelite caps. Adding plastic wrap will not extend the life of developers.
Another possibility are black rubber stoppers like the ones used in labs. These can be washed and used repeatedly. They do eventually become hard with age and will no longer seal properly. But they are cheap and can be used for several years.