The final choice between drug groups is your own. It needs practice, but making this choice on the basis of efficacy, safety, suitability and cost of treatment makes it easier. Sometimes you will not be able to select only one group, and will have to take two or three groups on to the next step. Another problem is that your P-drug may score favourably on an aspect that is of little clinical relevance. Sometimes kinetic characteristics which are clinically of little importance are stressed to promote an expensive drug while many cheaper alternatives are available.
Side effects are a major hazard in the industrialized world.
Not all drug induced injury can be prevented, but much of it is caused by inappropriate selection or dosage of drugs, and you can prevent that. For many side effects, high risk groups can be distinguished. Your ideal choice in terms of efficacy and safety may also be the most expensive drug, and in case of limited resources this may not be possible. Sometimes you will have to choose between treating a small number of patients with a very expensive drug, and treating a much larger number of patients with a drug which is less ideal but still acceptable. This is not an easy choice to make, but it is one which most prescribers will face.