Like Susanna, I would just grab them all too! I have four 301's and they are great to take to retreats and friend's houses because they are light, full sized, and have a great straight stitch. They also free motion quilt well.
I have a 401A that I just wanted and it sits on a shelf and looks pretty. I bought a 500 Rocketeer for the same reason as the 401A. I love its look but I haven't taken time to clean, oil, and lube so I can use it.
I have a 403 that I like as well as the 301's except that it doesn't have that nice built in handle. If I need decorative stitches at a retreat or friend's house I often take that one since it is much lighter that the Bernina 730.
I don't think you can go wrong with one of those machines.