Andrea. My first response is that if you are fairly new then this could be a pretty daunting initiative. With that said, I’ve used both choices and they both have pros and cons, and is difficult to provide a simple list. A lot depends on PMs capability with MS Project, process and who sets estimates, whether the estimates are primarily during selection or throughout the project, and probably a few more. The simplest solution is to use Resource Plans. It is designed to provide high, project level estimates. It does an OK job, but a couple things to consider off the top of my head. (1) it is very simple, which means it isn’t very functional. Changing existing estimates (moving them out, changing dates, etc. can be challenging. (2) I assume you are using Project Server 2013. Unfortunately, Resource Plans are replaced with Resource Engagements in Project Server 2016/Online which behaves very differently. No perfect answer, but hope that helps with some testing.