I think there is certainly a balance to be struck between hands-on learning via experience and didactic learning through lectures, reading, etc. I agree with the others that what type of program you look for should depend on what exactly you want to get out of your PGY1 year. As mentioned above, for the specialty I am going into (neurology), it is really critical to have a good foundation in general medicine.
Another important consideration is the level of autonomy a program offers for its interns. This is somewhat hard to discern on interviews, but I believe that it is one of the most important aspects of internship and how you really learn to "be a doctor". It is critical to look for programs that offer a good balance of autonomy (i.e. getting to make management decisions on your own) and back-up support (i.e. residents, attendings who are not too hands-on but willing to be there if questions arise or an intern is struggling). Besides the medical knowledge, internship (and residency) is really about learning to be an independent practitioner of medicine. That means experiential learning that gives you the confidence to make reasonable management decisions.
Believe it or not, diagnosis is a relatively small part of internship. I spend much more of my time on patient management. This is difficult to explain here, but involves knowing what to do in various situations and permutations of disease presentation to find the best management for a particular patient. For example, diagnosing acute coronary syndrome is fairly straightforward. However, knowing when and who to start on a heparin drip, how to manage a patient whose chest pain isn't relieved by sublingual nitroglycerin, has rising troponins, and let's say has end-stage renal disease involves not only knowing the standard accepted treatments but knowing how and when to apply these to the patient's particular clinical situation. With the above example, for instance, you wouldn't want to give the patient morphine (you would use dilaudid, for example).
Another important aspect is seeing a bunch of presentation of the same or similar disease. This allows you to understand the breadth of disease presentation how how varying presentations are managed differently. For example, an individual with 3 vessel coronary artery disease may be better managed by CABG, but not in all cases, for example the patient with multiple comorbidities that might make surgery too risky. That patient might be better served by PCI with stents. The only way you really start to understand these complex management decisions is to see many, many presentations of disease and learn when and why you would manage different individuals uniquely.
A final additional consideration is the level of comfort you would like to gain with managing patients. For example, if you plan to moonlight in general medicine to make extra cash during residency, it may be to your advantage to have a solid prelim/transitional year under your belt so that you feel comfortable doing this. Also, depending on your residency choice, you may want a higher level of comfort at managing patients' medical issues (i.e. a neurology program in which neurology serves as the primary team for patients). As a PGY2, I know I will at times be called upon to manage both the neurologic and other non-neurologic medical problems.
In the end, I would definitely try to avoid a malignant program and strike a balance between rigor and happiness (for some, the two actually go hand-in-hand). Hope this helps! 🙂