Which one performs best?

I would not approach it from the standpoint of I want to build container homes and then look for a site, I would have a site and think about what the best use of it would be and if it happened to be container homes then go for it.As John mentioned above appealing to the masses is the route to success here IMHO

Good Evening BP members, I am looking to take equity out of a very strong performing long term rental.

Does anyone know of a reliable site or resource to check zoning laws for Airbnbs or STRs in general?

Think of it like a dating site in that its purpose is to just bring the interested parties together, but if love is to bloom, it will take some work.

It provides links to each county office's sites for when you're doing research. 

Applicant is ok to show me in person his account information on his laptop, but doesn’t want to put his user name and passwords to those sites into RentRedi application.

Yep, it's basically a dummy company, customer service is a black hole, and when I ask for someone to verify my claim that Stephanie told me I could get out of my contract due to lack of performance, they can't even tell me if she's still in charge. 

I would make a site visit to where they live now and see how they treat the current property.

HUD publishes the Median Fair Market Rent on their web site for the entire country.