I would use a bus as it is neater. Only one lug on the block. I generally don't differentiate between engine starting and house loads as far as cable sizing. At least not much. If you have a Blue Seas 8023 for example, an 8 circuit panel and their most popular by far, it is rated at 100 amps. They recommend 2 AWG for cabling. The only way to effectively use a smaller gauge and still keep voltage drop to 3% or less is if the panel is very close to the battery. Blue Seas 2 AWG sizing is figured as 5 feet each way.
I also generally use a separate bus for the negatives near the panel, only running a 14 AWG wire to the panel itself for the indicator lighting. It keeps the panel neater.
Living aboard in Victoria Harbour