It's not just about the number of stitches, there are lots of other features that each of us *require* and *like* about different machines.
Features such as ....
Throat (harp) space
Stitch Regulator (for FMQ)
Integrated Walking Foot
Ability to stop needle up or down
Ability to drop feed dogs
Empty Bobbin Sensors
Thread cutters
Integrated embroidery unit (along with various options on the max size of the embroidery)
Ability to scale stitches (and embroidery)
Ability to change the position of the needle
Automatic threaders
Automatic tensioners
Start/Stop button (as opposed to using a foot pedal)
Knee Lifts
And on and on.
And there are also considerations of "quality". Is the brand and model from a reputable manufacturer with great reviews? Are the parts (especially the gears!) made from metal or plastic?
Pick just one manufacturer ... Janome, Bernina, Pfaff to name a few, and go to their website and look at all the machines starting with the low end model and work your way through to the top model and note the differences in features. You should also make note of the weight of the machine as that *can* be a clue as to the quality of the manufacture (i.e. if all the parts are plastic the machine will weight a lot less than a machine constructed out of metal).