I'm 186 cm tall, and I ride a size 60 (from 2017, but I believe the geometry is quite similar). I'm not sure how my inseam compares to yours, but based on height I would recommend the 57 for you. I like how my bike fits, but that's with a 90mm stem, and I would definitely not want the reach any longer. As djb points out, you can't compare the top tube to you current mtb without taking the addition reach from the rop bars + brake hoods into account - a 61 cm top tube on a touring bike like this is very long.

The best would be to try one out in a shop, or maybe try a similar model from an other brand if the Trek is not available in your area, to get a feel for how it fits.