One of the biggest challenges for me with Aquilonia is finding the perfect miniatures to represent them. I could go the historical route which would be early 100 years war British or French. One of my personal dislikes for that route would be using bascinet "pigs snout" style helmets, I just have a hard time imagining the Knights of Poitain or the Black Dragons using this style of helmet.
This has led me to do a head swap. I was using some Roundway miniatues Spanish medievals with a head swap with their line of Russian knights and a bit of grey stuff to sculpt on some capes. These particular figure are supposed to represent the Black Dragons (Elite Royal Aquilonian Guard Unit) and the Aquilonian king (Conan?). They are based with Mighty Armies in mind, but will still work for RRTK. I liked the outcome but I do need to find shields for them.
But I am sort of leaning towards the old Demonworld Empire figures. They have a semi-historical look without pin pointing it in a strictly historical setting. j
Anyways these are some ideas that I am riffing off of.