I have a really basic pfaff. It isn't electronic, doesn't have any bells or whistles (just a straight or a zig-zag stitch) but it does have dual feed which brings the top and bottom through evenly. They're also really reliable, my mum still uses the one she got as a 21st birthday present 40 years later!

You can usually get the dual feed effect on any machine with a walking foot. That should solve the problem with the layers not coming through evenly, otherwise you might want to try basting it with a spray to keep the layers together a bit more than just pins.

I wouldn't bother with anything more fancy, it's really not necessary for quilting. As long as you can adjust your stitch length you should be good to go