Best Castle age capped Civ

okay so a bit of context, i often play with some friends that are frankly not the best at this game (1300-1500 HD)

Recently they started wanting to play castle age capped games where imperial is locked. obviously they intend to turtle it out and make a large undefeatable teambase. to me this idea sounded both horrible and amusing at the same time but it did get me thinking:

Which civs would be very strong in a Castle age only game?

interrested in suggestions for ''normal'' games but also treaty games where i allow them to build upbe creative!

some civs i considered:

> Franks, cheaper castles good knights early castle age and throwing axeman to help defend vs ram masses

> Malay, cheap war elephant + skirms or archers as the main army (costs about as much as a knight while having more dmg and twice the hp)

> Spanish, Conqs are probably the best castle age unit in the game

> Persian, i dont mind missing fortified wall since i intend to be on the offensive, and w RoR expansions the non elites got trample damage.

> Magyar, Magyar huszar are pretty damn strong in the castle age