Basic research should be used as a means to elicit information but not a means by which to draw conclusions. Knowing this, begin with some internet searches in order to get a basic idea of which regional centers and industry experts may be the largest and the most successful.
Many regional centers have operated solely as 'sponsors' of a project so the data you may see may not be reflective of projects that were completely under the control of that regional center. As a developer you should also seek out sources of information that do not have a cost associated with them. Initial consultations are oftentimes without cost however you will want to make sure the individuals or regional centers you are speaking with actually have the experience, expertise and ability to undertake a project in the region where your project will be built. Regional centers have a limited geographic scope so not all regional centers can undertake projects in all regions.
When considering regional centers look at past projects of the regional center and try to determine if this is a developer operated regional center or if the regional center works with a host of developers. Look to see if the regional center has any long-standing relationships with highly successful developers.  Do not be afraid to ask questions and do not be afraid to ask very direct questions if your research turns up something you find concerning. If you have questions or concerns on a specific issue it is likely others have, or have had, those same questions or concerns. You should always be prepared to ask questions, get detailed answers to those questions and ask for ways to independently verify any of the information that is provided to you.
Any interactions with migration agents will stem from the nature of the relationship the developer has with the EB-5 offering. If a developer is operating solely as the borrower of EB-5 funds then a developer's interactions with migration agents, if any, should be limited to the developer's project and not the EB-5 offering that immigrant investors would be subscribing to. Developer's seeking EB-5 investment capital need a clear understanding of how they want to approach this funding source and what their duties, obligations and responsibilities will be if EB-5 investment capital plays a funding role in their project.