Choosing your kitchen chairs will depend on how you want to use them and also on how you want them to look. Kitchens get used for many different purposes, and not just for cooking. They are areas for eating, for using your notebook PC, for the kids to do their homework and for get-togethers with friends and family. So your chairs will also need to fit in with this variety of activities.
Take cooking first of all. Paradoxically, much of the activity in cooking is done standing up. Even preparing food such as peeling for slicing vegetables, fish, meat and so on is often done on a work surface which is at waist height, and which is used when you are standing up. This is not to say that you will never use a chair and do some of this work at a kitchen table, but what it does mean is that your kitchen chairs need to be as "storable" as they are "usable".
Having identified this as a first criterion, the next one is to have kitchen chairs that fit the different occasions and the different people who will be sitting on them. Easy to clean chairs are a high priority for many people, especially when you have kids who eat finger food and forget to wipe their hands on napkins afterwards. With the constant movement back and forth to the refrigerator, kitchen chairs get pushed back and pulled forward by sticky fingers. Plastic seating and metal frames, which are also likely to remain robust, which explains why they are a popular choice.
If on the other hand you have a farmhouse-style kitchen table, then you might well prefer to have wooden chairs to go with it. In this case be prepared for the corresponding wear-and-tear on your chairs. For very small children you'll probably need to lend a helping hand for then to have their chair pulled in close enough to the table. The wooden farmhouse kitchen chairs that go with the chunkier tables tend to be quite solid in themselves.
Some kitchens dispense with the kitchen table in favor of the breakfast bar. This is a surface which is higher and where the traditional chair is in fact too low for any comfortable use. In this case a bar stool model, possibly with a back to it, may advantageously replace the traditional chair.
This kind of "high chair" may also suit the chef who is busily preparing hot meals, jams or preserves, and soups, all of which may require periods of constant attention. Sitting on this kind of raised chair allows you to take the weight off your feet as you lovingly stir that homemade cherry jam at the critical point in its cooking.
Finally, remember that if you start out with just a few chairs, and then find that you need more afterwards, it's a good idea to check that the model that you select will be in stock for a few years so that you can add more of the same.