The new version of Digital Performer will be coming out for windows soon. It has been years since I have used it, but it has a reputation for having great midi capabilities.
http://www.motu.com/newsitems/digita...r-does-windows
It says it supports VST pluggins, but says nothing about VST3.
In the end I am not sure if the difference between Reaper's midi and other software's midi would be significant enough to make a change, unless you were doing a lot of midi orchestrations, and even then I am not sure.
Reapers midi reputation is, I think, a little out of date, mostly based on older versions and impressions made by those older versions, or just hearsay.