What are key factors that weight into who you chose, and why are those important?

Having multiple layers of shingles will add to the weight of the roof causing damage and you have no idea what is under them. 

Sometimes a high upfront acquisition fee, can be because the split is weighted heavily in the investor favor.

I personally place more weight on the long term numbers since you might only be living there for a year or two.

The management expense is usually the cash flow killer for investors, but they are worth their weight in gold when you account for the headaches and cleaning that needs to be done.

There are down payment assistance programs out there to lessen the burden for lower-income folks, but you will still end up needing some assets whether it be for closing costs or establishing a reserve for maintenance. 

And you're right I did put a lot of weight on maintenance expenses and vacancy. 

They're worth their weight in gold and it's a pass through cost.

However, appraisal courses are generally worth their weight in gold.

My feeling is, having the Liability under the LLC that you have personally, will lessen the motivation for them to go after you directly.