15 yr vs. 30 yr affect on cash flow

[Michael E.]

So imagine I have a generic property in a vacuum that I could finance in one of three ways (approximately):

30 yr loan => +$1000 cash flow per year

20 yr loan => Basically break even on cash flow

15 yr loan => negative $2000 cash flow per year

(all would be 20% down)

So I'm not a big time real estate investor that's always doing deals....I'm looking to own a small handful (1 to ~3) of properties to build long term wealth and generate some income to fund a potential early retirement in early 50's (maybe) and bridge the gap until I can tap into my 401k and IRA at 59.5 yrs old. So there's an incentive for me to have the property paid off when I'm 45-50 years old (15 or 20 yr loan), as opposed to financing for 30 years and then not owning it outright until I'm 60 (when I can access my 401k anyways).

BUT - I always hear about the dangers of negative cash flow. Does this still hold if the negative cash flow is due to aggressive financing, not the property itself?

Which option would you go with?