I'm just about to start in converting Perry's Wars of the Roses figures for Game of Thrones.
Houses Lannister and Stark are fine for this. High medieval fantasy concept. Plate for Lannister and the leather for Stark.
Hundred Years Wars figures would be equally ideal for house Stark
Brettonians from GW would be suitable too.
The Wildings could be a mix of WF germans and vikings. (Though I am using West Wind Games and Old Glory - Ancient Irish)
To get a more fantasy feeling you could use the orc weapons and bodies with human heads. Not sure of the fit but might work.
To go back to the original thread it needs to be more specific.
Fantasy men at arms in a mix of leather and plate armour with ...
To be honest it doesn't work as a generality.
Early Medieval Fantasy would be the Vikings and Saxons, Normans.
Medieval period would be 12th/13th Century. Crusades etc.
High medieval, 14th/15th Century - Hundred Years War and Wars of the Roses.
To get the 'fantasy' feel then you simply need to add spikes, and a range of horned helmets, wild shields and weird weapons.