Most scrappers I know use a 12”x12” album for the "family scrapbooks" and smaller (6"x6", 8"x8", or even 8.5"x11") books for themed albums.
3-ring binders or D-ring binders: These are just like the binders you used in school. This is my preference, though I have a hard time finding these in Victoria. A simple 3-ring center means you can add or switch around pages easily and a D-ring allows pages to lie flat. The best thing is that you can fit a lot of pages into a 3-ring binder.
Post-bound albums: The pages are bound into the album with three posts that can easily be taken out and more pages added in or removed. It is also somewhat easy to move pages around.
Strap-hinge albums: These albums have flexible plastic straps in the cover that run through wire loops embedded in each page. Binding is expandable but pages are not a readily available.