Valuable projects are those cared by many people, or at least many people can be convinced to care about them.
The conclusion should be derived from the input data in a logical way, with some reasonable assumptions.
Repeating previous studies should be avoided, unless an different result can be obtained. A novel project should either be a new finding, or bring us a new perspective on old things.
A feasible project means: 1) the data quality or the facility meet the requirement of the scientific goal; 2) there is a clear plan to achieve the goal.