It's a lot like buying a car. Some people like vintage cars; others want heated seats and power steering. Sewing machines are often not returnable, so it really is a good idea to take your wife to local dealerships and have her sit down and try out a wide variety of machines.
Decide on your price range first; otherwise you may end up looking at Lamborghini's when what you really need is a Prius. Deciding on your pricing upper limit eliminates a lot of machines.
In general, for an entry level machine, Janome and Brother brand machines tend to be the best these days. Stay away from low-end Singer, Elna, Bernette, etc.
Vintage featherweights are lovely machines. I have one. (Sold two others that I had acquired over the years.) However, they are very limited in what they can do compared to new machines. New machines in the price range of a vintage Singer featherweight will have such features as needle-down, built-in zigzag and decorative stitches, a stretch stitch (helpful when sewing children's clothing, which often requires knit fabrics -- especially for the easy starter patterns), the ability to move the needle off-center, etc.