We use a mixture of Mordheim and Malifaux terrain, mostly, with a few smaller 40k pieces for flavour. Mainly since that's what we used for our Mordheim campaigns and had around.
So, a lot of two and three story buildings, ground level is mainly three-inch wide alleys, bridges and dangerous slopes everywhere, lots of cover. Twelve inches is not uncommon. We've had a few rare 15" and 18" falls.