I work for the brokerage arm of a money manager/equity firm that buys, sells and leases real estate with it's clients' money. They buy portfolios all day.
Long story short, my best suggestion would be to present portfolios to institutional investors, equity firms, experienced real estate investment syndicates and corporations, and the like.
Those with the means, experience and resources to handle a portfolio or properties likely are buying cash or already have their financing in place. Interviewing lenders isn't a bad idea at all, but unless you've developed a working relationship, they won't be able to sell them as well as you can, and you will spend the same time probing them for their qualified clients who are buying your type of asset; where that same time can be spent researching and interviewing and probing actual potential buyers of your type of asset.
I'd say list/market the portfolio as a first option and go the route of finding lenders as a secondary route.