Good idea might be to take a look around at what's available, and choose a style you like, you're going to be looking at them for some considerable time, so make sure you like them. [broken link removed] have a range of styles on their site, that'd be a good start. There are many other suppliers, so shop around.
Closed gates will act as a deterrant to a casual burglar, much easier slip in through an open gate without being noticed. Won't stop a determined one though.
Leo