I have a Bernina 440 QE, and the features I like the most are the needle up/down button and the knee lift. Also, the feet are very easy to change, and the needle plate is very easy to remove to clean the lint out. I like the on/off button feature, too, and since the foot pedal plugs in on the side of the machine in the front in the same place the feed dog button is, it is very convenient. I use it when I am doing FMQ, and also when I am making eyelets.
The one option I would like to have is the automatic thread cutter; however, I try to chain piece as much as possible, so I can live without it.
Good luck in your search.