Hi Adrian, welcome to the KoW community.
Your Bretonnian army makes a good starting point for Kings of War. I’d suggest using that army to try the game and when you’re hooked (like us) you can pick the army that appeals to you.
The equivalent to Bretonnia in Kings of War used to be Brotherhood in 2nd edition. I used my GW empire army to play one. In 3rd edition, the game has evolved somewhat and the Brotherhood faction has split due to in-game lore.
Of these two factions, one especially might apeal to you. The Order of the Green lady is basically a combination of feudal knights with elemental forces (water&earth) from the forces of nature list. As @Boss_Salvage mentions, it’s a valid army. That said, the army is not particulary new player friendly as it’s got quite a few fiddly parts.
The other faction is the Order of the Brothermark. Lorewise, the less mythical parts of the Brotherhood joined up with Basilea (the lawful-good empire) for a more Byzanthian-themed human force. Game-wise this army -to me at least- is a bit of a disappointment . As it’s very similar (and less good) than it’s parrent list, I’d suggest using these models to build a basilean army instead. And this is very well possible with these models. For instance, here is my empire army representing a 3rd edition Basilean army and part 2.
Which brings me to the point I aim to make:
Your Bretonnian (human) army can be used as two main armies without any adjustments:
- Basilea (lawfull good humans following shining yet flawed deities)
- Kingdoms of men (A generic but suprisingly versatile and effective human army able to represent human armies from ancient egypt to 17th century europe).
With some adjustments, your army can also represent
- Order of the Green lady (A theme list from the Forces of Nature army adding in knights and men-at-arms)
- Order of the Brothermark (A basilean theme list)
*League of Rhordia (Kingdoms of Men theme list originating from GW Empire
So basically, having a human army sets you up for almost half a dozen armies with vastly different playstyles that may or may not apeal to you. I love the versality of humans.
That said, if you want something truly mythical or fantasy, you might want to explore one or more of Kings of War’s other options. There’s plenty of armies, each with a different playstyle.
All “full armies” (named parent armies) are valid choices with plenty of choice both model and game wise. Some “theme armies” (like the Brothermark listed above) are much more niche. While you can’t go wrong playing order of the Green lady, I would not suggest (for instance) Twilight Kin or Sylvan Kin to a new player.
If you have more questions, don’t be afraid to ask them. We Kings of War nerds love to answer the questions.