I've played both, it just comes down to preference. I think it's easier to use signs on keyboard but on controller you can turn on quick signs in the settings.
deathmarch is easier than most games' hardest difficulty choice ngl. but blood and broken bones is a solid choice imo. cuz under that it's too easy and might break immersion.
They both have the same learning curve so stick to whatever you are used to most. I tried both but obviously prefer kb/m because I have the most time on it.