I'm not really interested in the topic but had to comment on your choice of subject title.

What might be a few factors that can make a rental property a good choice for long-term investment?

It's an alternative to asking for additional security deposit.  

Alternatively, you can also attend local RE events and talk to other investors/buyers that are interested in buying the deal from you. 

The small details of finish choices, landscaping & staging really tied everything together to bring a home on the market that really stood out.

- As a buyer, are you able to stipulate that you will use a closing attorney of your choice? 

Alternatively if you do a cash out refi to pull out your equity you won't be taxed because you are technically taking on debt not making money. 

Personally, I would not recommend any ARV-dependent strategy right now, and that's 100x more true for beginners--and anyone attempting an ARV-dependent strategy should definitely be very conservative with their financial models, and have multiple alternate exit strategies available, in case they fail to hit their ARV. 

It's a personal choice.

I figure these are my two choices:1. pay off my own mortgage and increase my current heloc to make my first REI2.