seems to me it depends on what you are doing with your machine. if you are just creating the quilt top any machine with a good straight stitch and an up/down needle position would probably do just fine. if you are actually going to quilt with the machine the higher end machines are worth the money. if you are going to longarm or have someone else do that for you I wouldn't spend the money for bells & whistles you won't use.
I have a Viking sapphire 850. middle of the pack in price and love it but I do actually quilt with mine so it's worth the extra money for the larger throat & all the other fun things. good luck with your choice.