I heard that Maricopa, AZ is one of the good choices.

In terms of comps and understanding both sales & lease deals, as well as what space might be available by tracking lease expirations, it is absolutely the best choice out there. 

Additionally, there are often fees associated with belonging to an HOA, which can be an added financial burden.Ultimately, it comes down to your goals and deciding which choice will most effectively support them.

white isn't my first choice when I update rental units.

Plus in small town USA you don’t have a lot of choices.  

both have been solid choices

From my perspective, the new builds are so competitive with both the prices, closing cost assistance and rate buy-downs that they are a clear choice for anyone looking at turnkey options. 

I have heard that paying off your rental is not necessarily the best choice because of the deductions it allows for, but given the type of loan this house is mortgaged with, is it even possible to buy another home together and start renting this one out when I have a FHA loan on this one?

The choice depends on your business model.

And then today, when I called into tech support, I got lectured on my frustration and choice of words (note that I did not cuss nor was I rude to the rep on the phone and even explicitly stated that I understood it was not this particular phone rep's fault).