100 percent acrylic exterior high quality paint. There are many good brands. I think a low lustre looks better than satin for aluminum siding. The siding needs to be cleaned very well first too by power washing usually until all the chalkiness is removed.

Be careful when power washing siding. You can easily force water into places it is not supposed to go. Forcibly spraying at an upward angle is what you want to avoid. That will be difficult to do from the ground.

Echoing ionized comments. power washing is overrated.
You are going to prime this aluminum, aren't you? If you do and use the 100% acrylic you can probably expect and long term job.