Refinance in 15yr or 30yrs with different cashflow

There are a lot of experienced landlords here, so please educate me as I am really confused now:
15yrs loan, 4.375%, negative cashflow
30yrs loan, 5.125%, positive cashflow
I need to pay more principle of course for 15yrs loan, which causes the negative cash flow.
After looking at previous posts, I should take the 30yrs to get postive Cash. But, I pay more principle for 15yrs and I will get them back when I sell the home, so should I really care negative cashflow? Plus the interest expense is much smaller in 15yrs loan, so more rental income goes to principle, which will be mine later in sale.

So I am confused. Please help!! need decision this week, urgent! Thanks so much