The term "coffee machines" refers to a rather broad range on coffee brewing equipment, from simple percolators to costly espresso makers. So clarifying the whole issue of choosing the right machine, will require more than just one Q&A item. Still, we can begin by pointing out the main criteria:
1. How do you like your coffee? Just regular black brew or thick espresso? With or without milk? cold milk or hot milk foam?
2. How much automation do you want? Do you want the machine to do everything for you at the press of the button? or do you want to feel like a barista, doing most of the work "manually"?
3. To how many people at once you will usually make coffee? Is your machine going to be mostly used at home, making 1-3 cups at a time, or is it meant for larger crowds (e.g. in a small office)?
4. And then of course there is the question of budget. This should take into consideration, not only the cost of the machine itself but also of the coffee you are going to brew. In principle, coffee for coffee machines can come in all kinds and forms - from whole beans to coffee pods, depends on the machine.