I'm a family of Janomes and I'm sold. I bought mine new and got a special deal because I saw one online for much cheaper and got it at the online price through the dealer. My mom also got hers new, and I've never had problems with either machine. They both sew like a dream!
I have sewed on a Pfaff and a Viking before and both sew pretty much exactly the same as my Janome.
I have no experience with Bernina as the Bernina dealer is so snotty and is so rude to newbie sewers that I just haven't had thick enough skin to go in there and give one a go. Not to say that Berninas aren't good machines, of course!
Hope that helps!