Assuming your goal is to decrease your loan balance as much as possible, without doing almost any math, the REPAYE is almost certain to come out ahead because you get all this free money from the gov't that keeps your balance from rising. The difference in balances/rates between your private and gov't loans would need to be immense for any other plan to be superior. I'm going to ignore this small school loan, but it really doesn't matter.
Under REPAYE, let's assume your income is $45K, with 3% growth. Let's assume a 5 year timeframe -- the shorter the timeframe, the less it matters what you do. Using those numbers in a REPAYE calculator, using the national average for the poverty level, your payment would be $224 and the gov't would pay $1900+ each month. So your annual cost would be about $2700, but the govt would be paying most/all interest, so the loan balance would basically remain the same -- you'd still owe $200K on your govt loans. The private loan would grow, but not double. Assuming annual compounding, the growth of your loan would be 1.057^5 = 1.3 or so, so it would increase by about 30-35%. That assumes that you don't try to pay it off -- with only $224/mo on REPAYE, you might be able to pay down this private loan also. But, if you don't, at the end of 5 years you'd have paid $13500, and owe $200K on the govt loans, and $6600 on the private, for a total of $207K. (In reality your REPAYE would recalculate as your salary increases, so you'd actually pay a bit more than that -- but the difference is small).
Now, let's assume you pay down the private loan. If you plan to pay off the loan in 5 years, the payment is just under $100/month. You'd end up paying about $5800 total, and the loan would be paid off. But the $200K in loans would grow to $270K with interest. So you'd be much farther behind -- but you'd have smaller payments during residency. So it really depends on what's important -- minimizing loans, or minimizing payments.
I think the above is correct, although I haven't reviewed REPAYE in awhile. I'm also assuming that while in forebearance, your interest capitalizes. If not, then the two plans become closer together.
[GrumpyOldMan]
I hate to say this, but being this far in debt and not understanding how repayment works is frankly terrifying. How can you take out this much debt and not understand how this will be paid back?
[/GrumpyOldMan]