BSS ideal weapon loadout?

Little confused how I'm supposed to arm my nuns with guns. I know I have a lot of choice (flamer, melta etc), but is there a general better or all purpose loadout for my BSS?

I know the box doesnt have all my choices (locked in Retributor boxes), but would 1x BSS box and 2x Retributor boxes give me 20 BSS sisters with all the weapons i could need without kitbashing?