FHA vs Conventional will largely come down to your credit score, downpayment, use, income/DTI, and future plans.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

Quote from @Carlos Ptriawan: totally agree, key point is don't lose money by not having complete understanding of future risk.we're in the great collapse of CRE market and LP is destroyed because the passive investor is the dumb money, time is important but not to lose money is incredibly even more important , the total collapse in many commercial real estate sector is way beyond 2008 as it seems.Carlos, where are you seeing that "we're in the great collapse of the CRE market" ?

700 above scores. 

Having said that, another BiggerPockets member has discovered some new information that I find to be incredibly important information.

@Philip Jones we've helped our clients do over a hundred.As some of the lenders posting have pointed out, the challenges are:1) Property value and corresponding loan size2) Appraisals have much better comparables than 5 years ago, but may still be an issue.3) Property condition can be an issue via the appraisal4) Ownership seasoning - most lenders looking for 6+ months or incredible documentation for cost of improvements made.5) Most DSR lenders require professional property management.Always try a small local bank or credit union, but most will expect you to transfer your business bank accounts over to them. 

Rates have been coming down the last couple weeks and it's possible to get rates in the 6s for DSCR loans depending on the LTV  (loan to value) and borrower credit score. 

Eventually, with time and experience, your knowledge and confidence begin to align more realistically.This concept is incredibly relevant to real estate investing.I encounter this often: an investor seeks advice but quickly tells me how much they already know.

Often, these numbers sound incredibly high relative to the loan amount.

There are DSCR programs that go down to a 620 mortgage FICO score-higher credit scores will have better rates.