I would recommend starting with a list of "must haves", followed by a "would be nice to have" list.
For me, those must haves are needle up/down setting, motor speed control, good lighting, good automatic threader, good stitch quality on button-hole stitches, large table, and probably a few more.
Take it from there. There are well-known manufacturers and I find that the customers are generally very loyal to a brand. I, for example love Baby Lock. Others prefer Janomes, or Brother. Berninas are popular but on the pricey side. Go to a dealer and check out the features vs. price. Don't get sticker shock.
I want to test drive my machines to make sure we hit it off. There is nothing worse than an incompatible sewing machine. I ended up with one and was NOT happy. Not knowing your wife, I have no idea if she would appreciate a final product under the tree or if she'd prefer to be in on the decision. Have fun and pat yourself on the back for being a very supportive DH (that's Darling Husband in quilt-speak).