Decker, all you need is manty tarps to build your load and you can pack anything, I grew up using both, sawbucks are nice for hauling meat in utah panniers but I liked the deckers better for work. Also if you got one side heavier than the other you can adjust how it rides on deckers easier and without repacking everything. Also with either you gotta learn hitches. Also if you want to use panniers you can on a decker, alforjas hooks make it easy.
Decker with combination bars. That way you can use them with panniers when it's convenient or sling mante loads when that's the better option. It's a Decker saddle but instead of having the rounded hoops/bars, there's some way the bags catch. This is a Ray Holes saddle and their way of handling it is bars are squared off more instead of being rounded (panniers were empty in this photo so just buckled through the bars, with a load they hang like they would on a sawbuck). Companies have different designs for the bars but use the same basic concept.
I've used all three and the modified deckers are my favorite. They just add so much versatility it's amazing. Of course I've watched some old time packers and they can make about anything work with the right hitches and manty configurations.