Answer: Robert´s
Step-by-step explanation:
The most important thing before doing preliminary research is having a clear idea of what is the topic to be addressed. Ali´s strategy will probably get him information about writing techniques and rather general information about possible topics, which will be narrowed only by his impressions.
On the other hand, Robert going through his notes to narrow his topic will help him have a better idea of his research question and consequently of the best research strategy.