I'll chuck in my 2c worth
I've got an older Bernina 640-2 Favorit that does beautiful satin stitching (as well as other built in decorative stitches - I think there are 13). That machine is circa 1954 and everyone raves about the later Record models. You can drop the feed dogs on this machine.
I've also just got a Baer & Rempel Phoenix 283F - that's the freearm model, but you can look for a 282 or 283 with ZZ capability. I've heard/read that the German manufacturers were ahead of their time with their ZZ machines so if you want to get an early one, then that could be an interesting purchase. Plus they look pretty amazing!
I've also got a Necchi Supernova Automatica but it isn't working yet. I've heard they're fabulous as well, but engineered with close tolerances and require a lot of oiling. I have the cams and booklet for this one and the embroidery stitch combinations are seemingly endless...