I believe that many practitioners come across a desire to structure budgets around outcomes in many countries. The arguments around the advantages and disadvantages of outcome vs output-based budgeting are a common topic in many performance budgeting reform contexts.
From this perspective I believe that New Zealand model is one of the best ones, as it provides a good balance between outputs and outcomes. Though the NZ model often gets criticized for losing the sight of outcomes, it is important things to understand that the output focus in NZ framework is not at the expense of outcomes, but these two perspectives are intended to be mutually reinforcing. If there have been some gaps in considering the outcomes, this has not been because of some inherent fault of the model but because of weakening of focus over time and more relaxed government practices with Labour Party coming to the Government. NZ is trying to fix this by implementing performance audit and I believe no performance system will work well without such audit.
Any system, I believe, has its advantages and disadvantages, and I concur with those who think that the output focus and performance contracts between ministers and departments have more advantages than disadvantages. One of the key advantages, I believe, is that it is the pragmatic approach that works in practice, and it is difficult to fully appreciate that without having actually worked on those issues. In Armenia, for example, the Ministry of Health was insisting on structuring their appropriations around outcomes/objectives. They were so persistent, that we had to give in and let them try. When the Ministry had a chance to think about it in a practical way they decided to abandon the idea, as they came to the conclusion that this was impracticable.
Many countries that claim to operate outcome-based budget systems, in fact, use outputs as the basis of their appropriations (such as, e.g. Australia). If one looks at the appropriations closely it will be easy to see that they are formulated as outputs or functions although they may be labeled as outcomes. I have also come across a lot of cases, when people call outcomes what are actually inputs, e.g. by 20XX the funding for health will reach x% of total budget. There are also many cases when output quality indicators (such as improvement in the quality of services delivered) are confused with outcome indicators.
One of the strengths of the NZ model is its conceptual coherence, as well as being very clear and simple. It tends to call things the right names and does not confuse different concepts.
Some ministers' and politicians’ dissatisfaction with the output focus is partially due to distaste for focus on accountability - as it is a natural human instinct to try to avoid accountability if that is possible. It is always possible to claim that the outcomes were not achieved because some external factor out of one's control has interfered. It is much more difficult to blame on external factors in case of outputs - as their delivery is much more under the control of the relevant manager/entity.
This being said, it is also important to recognize, that in the end, a country needs to be managed - and managed well. So far, the best way to achieve this appears to be managing outputs while keeping track of outcomes, understanding the linkages and using this information in the planning process. This is what the NZ framework allows you to do.