15 year or 30 year mortgage?

[Cristina S.]

We're looking to purchase our first rental (investor couple mid 40's, early 50's respectively). 

We plan on borrowing about 60,000-70,000. 

Is it better to do a 30 year mortgage with approx. 200+ cash-flow margin or a 15 year mortgage with 100 a month cashflow margin?

We are looking to keep this property (and hopefully a few more in the future) as part of our retirement income.

Thank you so much for any views.