I agree, decide what features you want. You probably don't need a lot of fancy stitches, just maybe a few basic ones: adjustable zig-zag and blanket stitch. You might want to be able to move the needle position [I do this a lot!]
Also consider any extra feet you might want: 1/4" flange guide, 1/4" foot, open toe applique foot, walking foot [if needed for the type machine you want - don't need with a Pfaff], and an edge guide foot. How much do the extra feet cost???
Are you open to a good used machine? Many LQS's have them. I have also seen used machines in estate and yard sales ... just ask to try them out to make sure they really work and have all their pieces like a foot pedal and and a power cord.
Does the store offer support in the way of lessons? If they want you to pay for these ... walk away quickly!
Try the different brands and see what you bond with.
For example I could have had my mother's machine years ago but the way it was I knew I wouldn't use it as much because my kids would distract me and I would set the stitch - seen only in a little tiny window at the front of the machine, seen only if I scrunched down and looked right at it - on the wrong stitch and would get upset. Definitely not a machine I could bond with.
ali