Calderon and Vexx.
I always liked romances between royals and soldiers, or said royals' subordinates or guards, so both fit the theme. In my main playthrough, my character was in a relationship with Vexx before the events, and now has interest in Calderon.
I thiiink Vexx is my nº1 favorite, but I'll leave his route for last so yeah (I'm planning on doing all the guys' routes).