I love my new Bernina 530, especially the BSR (stitch regulator) for FMQ, but it is not all steel.....no newer machines are all steel. It probably has more steel in it than most others, though.
I also love my Janome 6600, with it's built in walking foot and it's extra large bed. Janome gives way more features for the $$$ over Bernina, and they are quality machines.
I also love my older late 60s and early 70s (really all steel) Kenmore machines for really heavy sewing.
If $$$ is an issue I'd go for a Janome, if you're at the stage in life where you have some flexibility, go for a Bernina.