Spool gun is best for most aluminum. It is classified as a GMAW process (gas metal arc welding, or mig process.) It uses your existing mig welder in most cases. I have two pics here. One is the cheaper miller and the other is the more expensive one. The Spoolmatic is the better, the spoolmate is the economy version. I used both extensively. If you don't plan on using it for heavy production, get the spoolmate, it will do just fine. I have a sample of the spoolmate welds. I am off work this week, but when I return I can post pics of the spoolmatic welds- very little difference. Spoolmatic is 100% duty cycle and is very good for an air cooled gun, Spoolmate is of a lesser duty cycle. For production use I would get a water cooled gun, but we are talking about 24/7 use. There is no reason that someone doing light work can't get by well using the cheaper of the two.
