For the most part you shouldn't be using either. Braid is designed to fish horizontal in the weeds as it is abrasion resistant and it floats. You will miss a lot of fish and not even know it, because you won't feel them. Mono is also mainly used for open water horizontal presentations because of its buoyancy. If you are jigging vertical, you want fluorocarbon because it has low stretch and sinks which gives you the most sensitivity. You just have to be a little more careful with your hook sets because it's easier to jerk it out of their mouth. I use the same when pitching jigs for lite bighting walleye in open water. However, there are exceptions. If you were using a drop shot rig and wanted to float your bait up off the bottom or wanted to slow down your lure drop you could use a mono leader, but I would still be spooled with fluorocarbon up to the leader.