What kind of bag should I bring?

Hi,

I'm going to be spending October traveling/backpacking around New
Zealand and am wondering what people think the best luggage-option is.
Would you bring (1) an internal frame camping backpack, or (2) a
rolling duffle bag? I've always used an internal frame backpack in the
past, but wonder if a rolling duffle makes more sense in this
day-and-age. I'm curious what people think.

Also, for those of you that have gone on "tramps," is it best to go on
them with a small rucksack or a big-mama internal frame backpack?

Thanks!
Ben