The only thing BB has over Mordheim is that its interface isn't a piece of shit.
Mordheim has much worse out of combat gameplay as it's basically a screen that you visit between missions and nothing more. You finish a mission, go to your management screen, do some stuff and back to another mission.
BB makes that feel much more natural and involved what with all the resource management and so on.
Also loot kinda sucks in Mordheim, even purple items don't feel especially powerful.
Level ups in Mordheim are also not so interesting as in BB. Here you get abilities that really change a bro every level.
Generally apart from maybe graphics (if you prefer 3d instead of 2d) and maybe setting, I can't find something better in Mordheim. And
I like Mordheim a lot mind you