My husband and son -- neophytes both -- bought my Brother Innov'is 450Q from a local sewing center; it was a "surprise" Christmas gift to me. It was a "floor model" and "discounted" but they still paid too much for it, in my opinion, because I think this machine has been abused, probably by people taking lessons who didn't know how to use it. The housing is "off" a little bit, as if slightly warped, and the extension table doesn't quite fit. I didn't know enough about computerized machines when I first got it to know if it had issues or not, but now it's behaving a little oddly-problems with uneven stitch length--so I need to take it in.
My first tried and true old Singer was used when I bought it about a thousand years ago and I never had any trouble with it. But that was then. Quality of everything has lessened, I think, and being computerized means more possible problems. I don't think I would have bought the Brother 450Q I have, but I don't know what I would buy in a modern, computerized machine. Good luck in your search!