Height
For scaling high locations often there is no alternative other than an extension ladder. Roof ladders are useful for working on rooftops but often an extension is the most convenient method.
For lower heights steprs and combinations are often the best solution - they are stabler and provide a place to put tools on.
Job
The type of task you will be doing is also important in ascertaining the type r required. If you are working with or near electricity a wooden ladder may Triple extension ladder often be safer than a conductive aluminium one. The type of equipment and tools needed will also help establish whether to use a platform or stepladder that provide a place for tools and equipment while ladder accessories such as tool trays can be fitted to other types.