It is really difficult to get a good deal from a bank, unless you buy with cash, in a quick transaction, don't require an inspection and buy in bulk.

Given you have such a low rate on your mortgage, you may be able to get some cash flow if you rent it out.

My focus is on buy and hold, cash flow properties. 

I was cashflow positive while living in the property and knew I would cash flow even more at my move out.

Buy something in class B neighborhood or emerging class C neighborhood with higher cash upfront low leverage to ensure you have enough cashflow in worst case scenario and see how it performs.

Timeline should be Three months: Save cash.

Do not focus on cash flow first in Philly or you will end up in a C-/D+.You HAVE to work with an agent who has been in Philly for a long time to have success and who owns properties there.

Most of these properties are going to take me 6-7 years to actually have positive cash flow.

Is it Cash Flow, Cap Rate, COC, all three or something else?  

We have been able to set aside some cash/savings over the past few years of marriage and are ready to invest in real estate.