Aluminium is more expensive.
Nearly all new houses here have colourbond installed. I have seen it on houses for 20+ years no corrosion. It is a little stronger and apart from a little fading with age it appears to be best value for money.
Al guttering I have not seen a lot of. Coloured Al, I don't know a lot about.
However Colourbond does very well.
What are the warranties like? How long have the companies been in business?
Google 'ABN lookup' to find out. It gives you some history as well (menu across the top)
Take a hi res photo when the job has been done. After a few years you can compare to check fading of the colour. Should have a limited guarantee on the colour fading.
Hope this helps
Cheers