There are so many different suppliers of ring binders that it can be extremelly difficult to define the best manufacturer for you. We will try to outline some of the key manufacturers and their products here;
Emgee ring binders have the broadest range of products, covering 2 ring binders, 4 ring binders as well as both the D and O binding types. The majority of their products are part recycled and the A4 2 D ring binders (pictured) have a clear plastic cover for inserting a front cover, back cover and also on the spine. Emgee also have a comprehensive range of A3 ring binders and A5 ring binders. The majority of their products have a PVC covering but they do supply the more cost effective board ring binders.
Bantex ring binders also have a very broad range of products - all with plastic, PVC or Poly covers and many made solely of plastic based products. They have products in the full range of capacity sizes from the most compact ring binders up to the largest ring binders. The Bantex snap ring binder (pictured) is a really nice product as it is translucent with various coloured tints.
Snopake ring binders have a slightly smaller range and do not have the really large capacity products but they really do have some stylish products at a good price. The Snopake Electra ring binders are an excellent product; they come in both A4 and A5 sizes and are translucent polypropylene which weighs less than normal plastic but is longer lasting and they have full length wrap around index holders on the spine and have business card holders. The Snopake professional ring binder is supplied with clear pockets and also some of the products have CD wallets inside - these products can work as display books as well as fulfilling the normal ring binding function.
Esselte ring binders cover the range from budget ring binders (pictured) up to some really classy presentation folders that would be ideal for displaying information at conferences and industry events. Esselte really specialise in the presentation folder range here so if that is the type of product that you are after then these are really worth a look.