The best scenario is a combination of all 3 or some other unfair advantage.BRRRR is a cute term, but let's call it what it actually is - you're taking on a mess and long list of problems that someone else could not solve.

Or what combination of both?

As of now, there is the community and masterclass combined. 

There are lenders that will allow up to high combined loan to values for helocs and/or second mortgages. 

If you have cash flow in a market where employment is concentrated in a few industries (such as automotive, entertainment, tourism, etc) then the cash flow is at greater risk that more robust economies.  

More of an entertainment set up.

Property was just a good combination of the "right place and right time."

Yes, Vermont towns have the option for a 1% local options tax in addition to the 12% combined tax above. 

Combination of owner carry and investment loan

I know that combined with decent project management skills can bring a deal home.