Aluminium was popular in the 1970s before UPVC came onto the market. Aluminium was strong with a slim section but was prone to really bad condensation. The outside of the frame was cold outdoors and warm inside, so you always had condensation running down the inside. The big makers such as Everest messed about with isolation inserts but the condensation was always there. It was a frequent topic of conversation down in the pub.
The moment UPVC windows came on the market in the 1980s, the end of aluminium was assured. The UPVC was more creaky but was virtually maintenance free whereas the aluminium models had to be placed inside a hardwood frame which needed to be waterproofed with Sadolin or similar every couple of years. So you need a ladder to do the upstairs windows.
Avoid the aluminium like a plague.