There is a real difference between a ladder you climb and a ladder you work from. Climbing is brief and you have both hands. Working means standing there for several minutes with a squeegee in one hand, leaning slightly, reaching the far corner of a pane. That is a different set of demands and a lot of the ladders sold in DIY sheds are not built for it.
The three things that matter are rung comfort, footprint and what the top does. Flat or D-shaped rungs stop the arch of your foot aching by mid morning in a way round rungs never will. A wide splayed base with a proper stabiliser bar turns a nervous ladder into a steady one, and it is the single cheapest upgrade most window cleaners never make. And a stand-off at the top keeps you clear of the glass, off the gutter and away from the frame you would otherwise be crushing.
Why a stand-off matters
That last one is worth labouring. Resting a ladder against the window frame is how uPVC gets marked and how leaded lights get pushed out of true. A stand-off puts the load on the wall either side of the opening and gives you room to work the pane properly rather than leaning around the stiles. If you are pricing up, it is worth reading a proper rundown of the right ladder for window cleaning before you commit, because the specification that suits a roofer is not the one that suits us.
Aluminium is lighter and most people buy it. Fibreglass is heavier and does not conduct, which matters the moment you are working anywhere near a service head or an overhead line, and in older Welsh terraces those are not always where you would expect them.
Whatever you buy, inspect it. Rungs, stiles, feet, the rivets at the hinge. A ladder lives on a roof rack in the rain and it does not last forever, and the day it fails is not the day you want to be finding out. ▪