One thing worth considering: This is not an all-or-nothing decision. This is also not a "do it all now" decision.
You can roll this into a tIRA and convert an amount that makes sense every year. In other words, as you get near a year end and have a pretty good idea what your annual income is going to be, you can convert Income - TaxBracketTopEnd - Exemptions - Deductions.
For example: (OMG, PLEASE DOUBLE CHECK MY MATH, I AM TERRIBLE AT MAKING NUMERIC TYPOS)
$80k retirement income
Married filing jointly, +1 dependent = 3 * $4,050
Standard deduction of $12,600
$75,300 top end of 15% bracket
$80,000 - $75,300 - $12,150 - $12,600 = 20,050 <- convert this amount and pay tax at your current tax rate
edit to add:
You can also add quite a lot if you're willing to pay at the 25% bracket. The top end there is $151,900.
There are some situations where Roth seems to really win out with taxes. The one I can immediately think of is if you inherit a tIRA and are going to be getting multiple RMDs. This is likely to turn your taxes upside down in retirement and have you paying quite a bit more in retirement.