The Singer 500 Rocketeer is another all metal machine. It uses the top hat cams as well and has built in stitch patterns too.
The singer 328 and 338 are are both good all metal machines. They use the flat cams. Lots of choices for patterns there. These machines are quite simple compared to the 401 and 500 series.
Then you have the Kenmores that use cams and / or built in cam stacks. They are excellent machines. In my NSHO the 158 series made by Maruzen / Jaguar are equal to and in my cases better than their Singer peers. I have several of them and they are great.
There are many other brands that made all metal ZZ and fancy pattern sewing machines, but these are what I'm the most familiar with so far.
Joe