Back when I was in high school, four-panel GMing screens — a huge improvement over three-panel screens — seemed to be pretty rare (my first was the one for Call of Cthulhu 5th Edition).
Six or seven years ago, the only way to get a hardback screen (one with panels like the covers of a hardbound book, rather than flimsy cardboard) was to buy one of White Wolf’s very sexy limited edition sets, which came with faux-leather hard screens.
I like hardback screens for the obvious reason: durability. My oldest cardboard screen (1990ish) is still kicking, but it definitely shows its age. Hard screens are also less susceptible to being blown over or knocked down, as silly as that sounds.
Best of all, these days they’re everywhere:
White Wolf  makes a four-panel hardback screen for every (or nearly every?) game line they publish. They’re well made, the fold nicely and they look great from the outside. Of the two I have (nWoD core and Mage), the Mage screen has a much more streamlined interior, but the nWoD screen has a more neutral exterior for use with other systems.
Exile Game Studio  just put out a very sexy four-panel hardback screen for Hollow Earth Expedition. I’d buy this to put my players in the mood for any pulp game, not just HEX (although HEX is a blast).
Pinnacle Entertainment Group  sells a customaizable, three-panel landscape-format screen (low, wide panels rather than tall, narrow panels). It’s made like the cover of a three-ring binder, with clear pockets on both sides to insert your own charts, artwork and info. The $27 price tag puts me off, but I love the concept.