Step 1: Aluminum vs Steel
If you have a choice between steel and aluminum systems, which is best? Steel is stronger and heavier than aluminum, so it's less susceptible to wind, ice, and tree damage, downspout extensions are less likely to be blown away or crushed at the ends, and the ladders won't crease the gutters wen they're placed between fasteners. Steel gutter components are zinc coated and carry 20- to 25-year corrosion warranties and up to 40-year paint warranties. And steel expands and contracts less than aluminum, which means less stress on sealed joints. As for the price, steel costs about 15% more than aluminum.
On the other hand, if you'll be working alone or with unskilled help, or if you're working 20 to 30 ft. above the ground, aluminum might be a better choice. It's easier to assemble and drive fasteners through, and much easier to lift from one end,. These are important advantages when you're clinging to a ladder. Because aluminum doesn't rust, warranties focus on paint durability, usually 20 to 25 years.