In addition to what Tammi said, I've liked White machines - I don't think I've seen a bad vintage one yet.
I betcha my favorite are the 15 clones. I don't know why. I guess because they are all alike but all different and they all work eventually. I haven't got a parts machine yet. fun place to visit & leave a pic if you find a clone...
http://www.quiltingboard.com/picture...p-t164361.html
Tammi, I think Elna, Viking, Bernina and Pfaff are nice machines - they are harder to work on.