I would decide which features I must have. On a second or backup machine, you may want to go for those features that your current machine is missing. Then I would look for at the different brands to see which machines meet my needs in my budget. Then I would read a lot of reviews on those machines.
I believe in talking to dealers. While I am no good at "dealing" in general, I have become a relatively good negotiator when it comes to sewing machines. Ask people in your area where to go. Who is good (sales and maintenance). Who will negotiate.....and have fun.