The biggest challenge in looking for a new machine is trying to quite the "noise". I was so confused when I was looking or a new machine earlier this year and the confusion only increased when going into a sewing machine store.
I finally made a list of the features that were important to me, then downloaded the online brochures and features lists which helped me to match what I wanted. I was able to weed out models that wouldn't meet my needs.
When I whittled it down to 3 or 4 models/brands, I went in and sewed on them. At that point, I could decide if I liked the feel of the machine.
For example, I was so ready to just walk in and buy a Viking since I already had one and was feeling a bit of brand loyalty. Until I sewed on it. I didn't like the way it felt to me.
I ended up with a Janome Horizon 7700. The only thing I hate about it is the manual. :)